Populations have declined substantially due to severe hunting, local insurgency, and industrial exploitation of habitat.

Genetic analysis shows that the closest living relative of the sambar is most likely the Javan rusa of Indonesia.

The appearance and the size of the sambar vary widely across its range, which has led to considerable taxonomic confusion in the past; over 40 different scientific synonyms have been used for the species.

[3] Adult males and pregnant or lactating females possess an unusual hairless, blood-red spot located about halfway down the underside of their throats.

[11] The sambar is distributed in much of South Asia as far north as the south-facing slopes of the Himalayas in Nepal, Bhutan and India, in mainland Southeast Asia including Burma, Thailand, Indochina, the Malay Peninsula, Indonesia (Sumatra and Borneo), Taiwan, and South China, including Hainan.

[1] In 2023, a study showed that sambar deer had returned to Singapore due to several escapes from zoos, after it has been believed to be extirpated from the island country.

[13] The sambar prefers the dense cover of deciduous shrubs and grasses,[11] although the exact nature of this varies enormously with the environment because of its wide Asian range.

[3] Like most deer, sambar are generally quiet, although all adults can scream or make short, high-pitched sounds when alarmed.

[citation needed] Sambar feed on a wide variety of vegetation, including grasses, foliage, browse, fruit, and water plants, depending on the local habitat.

[3] Sambar have been seen congregating in large herds in protected areas such as national parks and reserves in India, Sri Lanka, and Thailand.

In Taiwan, sambar along with sika deer, have been raised on farms for their antlers, which they drop annually in April to May and are highly prized for use as knife handles and as grips for handguns.

[11] Sambar are capable of remarkable bipedalism for a deer species, and stags stand and mark tree branches above them with their antlers.

[11] Despite their lack of antlers, female sambar readily defend their young from most predators, which is relatively unusual among deer.

[11] When sensing danger, a sambar stamps its feet and makes a ringing call known as "pooking" or "belling".

The male stomps the ground, creating a bare patch, and often wallows in the mud, perhaps to accentuate the colour of his hair, which is typically darker than that of females.

[3] Large, dominant stags defend nonexclusive territories surrounded by several smaller males,[15] with which they have bonded and formed alliances through sparring.

When sparring with rival males, sambar lock antlers and push, like other deer, but uniquely, they also sometimes rear up and clash downward[11] in a manner similar to species of goat-antelope.

Sambar were introduced into Victoria at Mount Sugarloaf in the 1860s, in what is now Kinglake National Park, and at Harewood Estate near Tooradin.

[21] They quickly adapted to the Koo-Wee-Rup Swamp and thereafter spread into the high country, where in 2017, numbers were estimated at between 750,000 and one million animals.

In Victoria, sambar are listed as a threat to biodiversity under the Flora and Fauna Guarantee Act 1988 because they reduce the number of native plant species.

[25] The spread of sambar has been steady in both New South Wales and Victoria, with animals being seen on many southern Victorian beaches since 1980, and as far east as Western Port and the outer suburbs of Melbourne.

[26] This allows a landowner or other authorised persons to remove problem deer within private property at any time and are permitted to hunt under spotlight, which is prohibited on public land.