The White-tailed Deer is a medium-sized deer with slender legs and a long tail covered in long hairs. The general coat colour is greyish brown in winter and reddish brown in summer. Throughout the year, the belly and chin are white, as are the backs of the lower front legs and the insides of the hind legs. There is also a white throat patch. The face is the colour of the body except for a lighter coloured or white eye-ring, a white band at the rear edge of the black, naked nose, and white inside the ears. There is a small black patch of hairs on the chin. The underside and edges of the bushy tail are white, as are the hairs on the rump immediately under the tail. But the upper side of the tail is usually the same colour as the upper body, or in some individuals is a darker brown. Young of the year are reddish brown with horizontal rows of white spots on the upper body.
The White-tailed Deer has at least five types of glands on its body, three of which are usually visible. There is a small antorbital gland in front of each eye, and a tarsal gland on the inside of the tarsus. A small metatarsal gland (less than 40 mm long) at the lower end of the metatarsus often with white hairs in the centre. The interdigital glands between the main toes are indicated by small patches of white hair, while the nasal and poorly developed frontal glands require more invasive examination. Biologists are uncertain whether the White-tailed Deer has caudal (tail) glands. Females have four inguinal teats.
Antlers of adult males consist of a main beam that curves up and forward over the head. Above the bur is a moderately long brow tine branching from the main beam above the eye, followed by three to five longer, upward pointing tines that are usually unforked. Yearling males develop a pair of either single spikes or simple forks; the brow tine does not develop until the second year. Like Mule Deer, atypical antlers with as many as 25 points have been found in White-tailed Deer from B.C. The skull of the White-tail has shallow lachrymal depressions in front of the orbits, and the vomer divides the posterior nares vertically into two sections.