They will stand flat-footed. The mandrill range follows the moist evergreen rainforest of the countries of Cameroon, Congo, Equatorial Guinea, and Gabon in central West Africa. The coat is olive-brown to brownish black, with a dull white to gray underbelly. The male has a bright red, white, and blue face. Two grooved nasal ridges are electric blue with a bright red midline that runs between the ridges, extending forward to the muzzle and the area around the nostrils.
White fur surrounds the red-lipped mouth under which is a yellow beard.
The buttocks and skin around them have a lilac tinge which becomes reddish purple at the edges. The bright color of the skin of these animals becomes more pronounced when they are excited. It has been suggested that the bright rear coloration serves as a way for the lead male to be seen amongst the vegetation of the forest and may also provide social and sexual signals. The mandrill has the longest canine teeth compared to skull size of all mammals. Its 2.5 inch long canines are used as weapons in social displays or fighting.