The vaal rhebuck has a body length of 105 – 125 cm and weighs 18 – 30 kg. The thick, wooly coat is grayish brown above and lighter below, with the inner thighs and underside of the bushy tail white. The fronts of the lower legs are darker. The body is small, with long, graceful limbs and a slender neck. The long ears are slender and pointed. There is a dark facial blaze, and the nostrils are bulbous and black. A white eye ring contrasts sharply with the black-lidded eyes. The stiletto-like horns are found only in males, and rise directly above the eyes. Bent forward slightly, they grow 15-29 cm (6-11.6 inches) long.
Active during the day in sporadic bouts of grazing and resting, the rhebuck generally rests in shade during the noon hours. While the rest of the herd forages or rests, an appointed ‘sentinel’ watches for signs of danger. If a threat appears, this guard makes a cough-like grunt to alert the rest of the family, and then leads the group to less accessible ground.
The rhebuck has a jerky, rocking gait, and when in flight it holds its tail erect, displaying the white underside. An agile climber, the rhebuck is also a good jumper. The dominant male in a harem herd is territorial, defending a central home range from intrusion by other males. This home territory is generally 15-80 hectares in size, smaller in the summer and larger and at lower altitudes in the winter. Males are extremely aggressive during the breeding season, with conflicts quickly escalating from posturing and vocalizing to serious fighting, where it is not uncommon for one of the contestants to be killed.
Mating occurs in April, with births taking place in late November and December. The young lie hidden away from their mothers for as little as a few days to 6 weeks after birth. Only a single calf is dropped. Sexual maturity begins at 1 – 1 ½ years.
Vaal Rhebuck live up about 8 – 10 years.