The Diana Monkey is among the highly endangered species. Among all African monkeys, the Diana monkey is the least known. Its body is medium sized with long legs and a slim built. Its long tail is often curved in the shape of a question mark sign. Length of a male tail is 29.92 to 35.43 inches (76 to 90 cm) and that of a female tail is 20.47 to 28.74 inches (52 to 73 cm). It has a black face consisting of a white brow line, beard, and cheeks. The inner side of its arms and the frond part of its chest are also in white, while its tail, belly, and outer limbs have a covering of black fur. It has a prominent white stripe running diagonally down its outer thighs and its rump bears cream or red fur.
Although size of males is significantly bigger than that of females, both genders have more or less similar appearance. Weight of an adult male monkey is about 11.02 to 11.9 pounds (5 to 5.4 kg) while the female adult body weighs about 8.81 to 11.02 pounds (4 to 5 kg).
Common habitats of this threatened primate include primary and a few secondary rainforests as also semi-deciduous and gallery forests.