A fluffy white bib appears below the face. The adult male, characterized by a blue scrotum and a long, prominent muzzle, is twice the weight of the female. Pruess's guenon is found on Bioko Island and in the Oban hills and Obudu of Cameroon but primarily on the north-western side of Mt. Cameroon between 1,000 m and 1,800 m., as well as in a few patches of isolated forest on the grasslands of Cameroon. The monkey is most common in montane forest and is rare in lowland forest. The monkeys travel in groups of two to twelve animals consisting of a single adult male and one or more females with their offspring.
Males sound a deep, two-part booming call in the morning and at dusk.
Pruess's guenons eat fruits, seeds, leaves, and flowers. Pruess's guenon is one of Africa's ten most endangered monkeys. The monkey has suffered substantially from the clearing of Cameroon montane forests and the establishment of access roads for hunters. Being relatively large bodied and semi-terrestrial, it is an easy target for hunters.