The Greater mouse-deer is an even-toed ungulate. Although very small for an ungulate, the greater mouse-deer is one of the largest members of its genus. It has a small, triangular head with a small, pointed, black nose and large eyes. Its long legs are as thin as a pencil. The hind legs are visibly longer than the front legs. The body is rounded. The fur on the upper part of its body is grey-buff to orange-buff. On the sides, the fur is quite pale, but darker along the midline. It is white underneath, more specifically on the neck, stomach, chest, and chin. The male has neither horns nor antlers but has small "tusks" - elongated canines in the upper jaws.
Greater mouse-deer are found in Sumatra, Borneo, and smaller Malaysian and Indonesian islands, and in southern Myanmar, southern Thailand, peninsular Malaysia, and Singapore. They live near water, in tropical forests and mangrove thickets.
Greater mouse-deer are terrestrial but spend time in wet, swampy areas. They are solitary, rather trusting but delicate animals. They are nocturnal and use small trails through thick brush in the forest. The males of this species are very territorial, marking their territory with feces, urine, and secretions from the intermandibular gland under the chin. When angry, the males beat the ground with their hooves at a rate of four times per second.
Greater mouse-deer breed throughout the year and the females spend most of their adult life pregnant. When the males are ready to mate, they rub a large gland on their lower jaw against the female to determine whether she is ready to mate. If she is not ready, she responds by walking away. Greater mouse-deer usually produce one young per birth, after a gestation of 152-155 days. Fawns are well-developed and immediately able to stand; they are fully active after 30 minutes. The young stand on three legs while nursing. They are weaned at 2-3 months of age and both the males and the females become reproductively mature when they are 4.5 months old.
Greater mouse-deer are threatened by loss of habitat through rapid deforestation. They also suffer greatly from overhunting for food and are very popular in the pet trade.
The IUCN Red List and other sources don’t provide the number of the Greater mouse-deer total population size. Currently, this species is classified as Least Concern (LC) on the IUCN Red List but its numbers today are decreasing.