[1] The red-eared guenon is a small, colourful monkey with distinctive facial markings which involve blue fur around its eyes, a brick-red nose and ears, and yellow cheeks.

[4] There are two recognised subspecies, which are listed below with their distributions:[5][4] The red-eared guenon is found in primary and secondary lowland tropical and sub-montane moist forest, and sometimes lives in close proximity to humans, as on Bioko.

[1] The red-eared guenon is omnivorous and has been recorded eating fruit, leaves, shoots and insects,[6] the latter are important for nutrition, especially for pregnant and lactating females.

The red-eared guenon normally forms groups consisting of at least one adult male and around ten females with young which are not as hierarchical as some primate societies.

The breeding biology of red-eared guenons is little known but similar species give birth to a single infant every one to three years, with pregnancy taking five or six months.