Previously eleven lion subspecies were described. Afterwards the lion was divided into two subspecies: the African lion (Panthera leo leo) and the Asiatic lion (Panthera leo persica). However, more recent studies indicate that lions from Asia and West and Central Africa are more closely related to each other than to lions from Eastern and Southern Africa. These two main divisions of lions are not homogeneous as there is genetic subdivision within each, with more genetic variation and deeper divergences within the Eastern and Southern branch than within the Asian plus West and Central African one. Based on these recent genetic studies, two subspecies of the lion are recognised:

• Panthera leo leo in Central and West Africa and India, formerly throughout North Africa, South-East Europe, the Middle East, Arabian Peninsula and South-West Asia
• Panthera leo melanochaita in southern and eastern Africa. 

The contact zone between the two subspecies lies somewhere in Ethiopia.

The lion has a muscular body with very strong front paws. Its fur coloration ranges from tawny and grey to yellowish red and dark brown. The colour of its nose gets darker with age in both sexes and the manes become more prominent and darker with time. The Asiatic lion has a longer tail tassel and a smaller, shorter mane than the African lion. Due to the less prominent mane on top of the head of Asiatic lions, their ears are always visible. Male Asiatic lions have also a more pronounced hair tuft at the elbow than their relatives in Africa. The most striking feature, however, is the Asiatic lion’s distinctive belly skin which is only rarely seen in lions inhabiting Africa. About 50% of the Asiatic lion skulls from the Gir forest have bifurcated infraorbital foramina (small apertures which permit passage of blood vessels and nerves to the eyes), which has not been recorded in African lions. 

The Asiatic lion is categorized as Endangered in the IUCN Red List. Today, the only representatives of the Asiatic lion are found in a single isolated population in the Gujarat State, northwest India. Previously, the Asiatic lions inhabited most of southwest Asia.

The lowest number of Asiatic lions was detected during the 1880s when only a few dozen individuals remained in the Gir Forest Sanctuary. Owing to timely protection, the Asiatic lion managed to survive. The first census of Asiatic lions, based on individually recognizable pug marks, was conducted in 1936 and yielded an estimate of 287 adults. In 1950, over 200 lions were estimated in the Gir forest, showing that the lion population was increasing with the enforcement of strict protection. Subsequent censuses between 1968 and 1979, based on counts of animals at live buffalo baits, estimated the population at around 150-200 adults. In 2005, the population was estimated at 291 individuals in the Gir Forest and 68 outside of the protected area, numbering a tot al of 359 animals. Presently, the Asiatic lion population is considered to be stable. The total population size is estimated at approximately 297 lions in the Gir National Park and adjoining areas and at around 114 individuals outside the park, totalling some 411 animals. In the Gir forest lion density varies between management zones and depending on terrain, habitat and human influences. Maximum lion density was estimated in the East of the Gir with 16 animals / 100 km². In the West and Central Gir, lion density was estimated at respectively 12 and 6 individuals / 100 km².

The Asiatic lion once had a very wide distribution ranging from Syria through Iraq, Iran, Pakistan and most of northern and central India to parts of eastern India. Asiatic lions inhabited large areas in North and Central India and occurred in the states of Punjab, Haryana, Rajasthan, Uttar Pradesh, Madhya Pradesh, Gujarat and western Bihar. It became extinct in Eastern Europe at around AD 100 and in Palestine around the time of the Crusades. In all other areas, the Asiatic lion remained widespread until the mid-1800s. The invention of firearms and widespread indiscriminate hunting led to its extinction over large areas. In Syria, the last report of lions dates back to 1891.By the late 1800s the lion had disappeared from Turkey while in Iran and Iraq it was last recorded in 1942 and 1918 respectively. In India, lions ranged east to the state of Bihar but they declined rapidly due to heavy hunting pressure and habitat loss. By the turn of the 19th century the Asiatic lion remained only in the Gir Forest in Gujarat, India. Presently, lions are also found outside the Gir Protected Area such as in forests of Girnar, Mitiyala, coastal areas of Sutrapada-Kodinar, Jafarabad-Rajula up to the Savarkundla and Palitatna hills covering an area of around 10,500 km². 

The Asiatic lion is found predominantly in forested habitats while the African lion mostly inhabits Savannah ecosystems. The Asiatic lions show a preference for moist mixed forests, followed by mixed forests, savannah habitats and Teak-Acacia-Zizyphus. During the day, Asiatic lions seem to prefer densely vegetated areas but at night their movement is more widespread and they may even move through agricultural fields and human habitations. Dense vegetation within forested areas thus allows lions to escape from the heat of the day and also provide cover at a time when human activity is likely to be high. 

The Gir Forest is a dry deciduous forest dominated by teak (Tectona grandis) in the west and in the drier parts in the east predominantly vegetated with acacia thorn savannah. The Gir Forest was reduced to less than half of its original size of 2600 km2 in the last century and most of it remains in the Gir National Park and Wildlife Sanctuary which now covers an area of about 1800 km2. The Gir forest is surrounded by cultivated landscape. 

Asiatic lions are mainly nocturnal and crepuscular. They spend major part of the day resting. Similar to African lions, the Asiatic ones live in a complex social system but the pride structure differs and even varies locally based on resource availability. The pride size of Asiatic lions (measured by the number of adult females) tends to be smaller than in African lion populations. In the Gir forest, most prides consist of only two females. A radio-telemetry study in the Gir Forest, from 2002 to 2007, even revealed an average female groups size of only 1.3 animals. In African lion populations in contrary, pride size may reach up to 18 adult related females with their offspring along with one to seven males. The core of such prides, the females, tends to stay stable while young males disperse and adult males may shift pride status under competition after two to four years. The females of a pride hunt in smaller territories than the males. Male coalitions and female prides have been found to hunt and feed independently. Coalitions of males defend home ranges containing one or more groups of females.  In contrast to the African lion prides, Asiatic lion males in the Gir forest generally only associate with their pride females during mating. Breeding Asiatic female lions defend resource based territories while male coalitions maximize coverage of female groups. The lesser degree of sociality in Asiatic lions of the Gir forest compared to that of lions in Africa maybe is a function of lower prey availability and the availability of livestock.

Lions are very vocal and their roaring is audible over several kilometres. Female as well as male lions scent mark. In the Gir forest, home ranges of male lions vary between 11 to 174 km² and the home ranges of females between 26 and 43 km2. Intensively used core areas, are much smaller with around 10 km² for males and 5 km2 for females. A radio-telemetry study in the Gir forest estimated an average home range of 85 +/- 54 km² for males and a home range of 48.2 +/- 10.6 km² and 35 +/- 7 km² for females.  Home ranges of male lions overlap considerably and also female ranges do overlap with each other. The average dispersal distance of Asiatic lions was estimated at 26 km.

The reproductive season of Asiatic lions takes place year round. However, mating seems to peak during winter and based on sightings of cubs, there seems to be a birth peak from late winter to early summer. The gestation period lasts for around 100-119 days and the birth interval is 18-26 months. The age of first reproduction varies for females from 3 - 4 years and for male lions 5-8 years. Breeding declines for females with 11 years of age. In 2010, female - male ratio in the Gir landscape was estimated at 0.63.

Juvenile mortality is around 33%. Infanticide can be quite high, causing up to 60% of cub mortality and seems to occur especially in the first year of birth. Inter-birth interval is around 1.37 years and is higher when cubs of the previous litter survived to independence. In 2010, adult survival rate in the Gir forest was around 92% and mortality was mainly (66%) due to natural causes. 21% of the mortality in adults was due to accidents which occurred outside the protected area and 13% of lions died of un-identified causes. Thus, human-caused mortality was still substantial. 

The Asiatic lion preys mainly on ungulates such as on small deers and antelopes. The sambar deer (Rusa unicolor), the chital (Axis axis), the chosingha (Tetracerus quadricornis), the chinkara (Gazella bennetii), the wild boar (Sus scrofa) and the nilgai (Boselaphus tragocamelus) make part of their diet. Asiatic lions also prey on porcurpine (Hystrix indica), common langur (Semnopithecus entellus), rufus tailed hare (Lepus nigricollis ruficaudata) and peafowl (Pavo cristatus) and take livestock. Nilgai and wild pig are common wild prey species found outside of the Gir forest protected area. In a study in the Gir forest looking at kills of Asiatic lions, kills of domestic animals constituted 56% of all detected kills. However, these kills were mainly found in the revenue areas and periphery of the park. A scat analysis conducted in the same area resulted in only 14% of domestic animals in terms of the relative number of individuals consumed and 86% of wild animals, with chital and sambar being the main prey species. However, in regard of consumed biomass, livestock made up 27%. The proportion of livestock taken by Asiatic lions seems to be influenced by the abundance of wild prey and varies between seasons. Significantly more wild animals were taken during summer when prey was concentrated around water sources.  Within the protected area, lions predominantly consumed wild prey in proportion to their availability. Outside the protected area, however, livestock seems to be the major prey and lions seem to depend considerably on domestic animals.

The Asiatic lion is included in Appendix I of CITES and fully protected in India. It is categorized as endangered under Schedule I of the Wildlife Protection Act (1972) of India. The population of Asiatic lion has been steadily increasing in response to successful management and conservation initiatives spanning over the last five decades. Management interventions, such as reduction in livestock grazing and control of fire, have led to vegetation recovery and increase in wild ungulate populations. The Asiatic lion population is now expanding and moving throughout the Greater Gir Landscape. This landscape, where the last population of the Asiatic lion remains, is of outstanding importance for the long-term conservation of this species.

The Asiatic lion lives in a landscape where people have a high tolerance and consider lions as part of their natural heritage. However, to maintain this positive attitude of local communities in the long-term, it is needed to improve husbandry practices and economic incentives as well as human safety in the Greater Gir Landscape. Of concern is the human-lion conflict mainly outside the protected area, where human and livestock density is higher. The coexistence of humans and lions, thus conflict mitigation and the promotion of positive public perceptions of lions, is essential to can continue with successful Asiatic lion conservation. It may also be necessary to create corridors to enable free movement of excess lions between reserves or isolated forest patches.

Theoretically, the captive population of Asiatic lions can be considered as a second population. A Species Survival Plan (SSP) was established by the American Zoo and Aquarium Association (AZA) in 1981 to manage the over 200 Asiatic lions held by western zoos. A studbook has been introduced to record the genetic and demographic data of the species. However, only two of the animals of the SSP-managed population were pure Asiatic lions and the programme was stopped. In 1990 a new programme was started, the European Breeding Programme (EBP) with two male and two female Asiatic lions of known pure genetics coming from India. In India, a captive breeding program with the idea to crossbreed Asiatic and African lions was already started in the late 1980s at the Chhatbir Zoo. The program was stopped in 2002 after many of the lions died due to a disease. It was decided to launch a new captive breeding project, but this time with genetically pure Asiatic lions from other zoos in India. A breeding centre has been established at Sakkarbaug Zoo at Junagadh where around 180 Asiatic lions have been bred in captivity so far.

In order to maximize the genetic diversity and reduce the risk of extinction through an epidemic outbreak, it is advised to establish at least one more wild population of Asiatic lions. A first attempt to establish a subpopulation was made in 1957 when Asiatic lions were translocated to the Chandraprabha Wildlife Sanctuary in eastern Uttar Pradesh. The attempt failed due to various reasons. First the lion population in the Wildlife Sanctuary increased from three to eleven individuals but afterwards all lions disappeared most probably due to poaching by shooting or poisoning. Currently, the Palpur-Kuno Wildlife Sanctuary in northern Madhy Pradesh is identified as the best area for establishing an Asiatic lion population since human disturbance is considered to be relatively low with 13,000 people and around 16,000 livestock living in the proposed area.  With assistance from the Indian Government a twenty year project was initiated in 1995 to establish a disturbance-free habitat for the lion reintroduction. In order to have adequate space for a free-ranging population of lions, the challenging task of re-locating resident communities has been successfully achieved as it is risky to move lions into an area where generations of people have no experience with large felids. The final implementation of the project is awaited.