The mona monkey is native to the lowland forests of eastern Ghana, Togo, Benin, Nigeria and western Cameroon. It has also been introduced into Grenada and São Tomé and Príncipe. Although mainly a forest species, it is able to adapt to heavily degraded forest, gallery forest in savannah regions, and mangrove forest in the delta region of the Niger River, and is generally the commonest monkey near rivers.

It lives in groups of up to 12 in forests, though larger groupings do occur. It mainly feeds on fruit, but sometimes eats insects and leaves. The mona monkey has brown fur with a white rump. Its tail and legs are black and the face is blue-grey with a dark stripe across the face. The mona monkey carries food in cheek pouches.

Fully grown males are 40-60cm long, 

Its conservation status is near threatened.