Mandrills reach a height of about 80 cm. The species is characterized by a large head, a compact body with long, powerful limbs, and a stubby tail, which is held upright. The wide rotating range of the clavicles enables climbing trees, the quadrupedal walk, and the functioning of the arms. Opposable thumbs allow these monkeys to grasp tree branches. Both sexes have paired mammary glands in the chest region.
The pelage is an olive green with paler underparts. It has a brilliantly colored blue to purple naked rump. A mandrill's face has a red stripe down the middle of the muzzle and aroung the nostrils, while the sides of the muzzle are ridged lengthwise and colored blue. This helps to distinguish this species from drills which have jet black faces. Mandrills have red fur patches above the eyes and a yellow beard. These colorings are duller in females and juveniles than in adult males.
These animals are reported to have average weights of 11.5 for females, and 25 kg for males. Males are significantly larger than females and may weigh up to 54 kg.
The head and body measurements range between 610 and 764 mm.
Range mass: 54 (high) kg.
Average mass: 11.5-25 kg.
Range length: 610 to 764 mm.
Other Physical Features: endothermic ; homoiothermic; bilateral symmetry
Sexual Dimorphism: male larger; male more colorful; ornamentation