The species is regarded as endangered by the IUCN as well as by the United States Fish and Wildlife Service, the chief dangers to them being habitat destruction (they are now virtually confined to coastal areas) and hunting for bushmeat.

Diana monkeys retreat to the upper levels of the trees at night, though they do not make nests, preferring to sleep on branches.

The monkeys, in turn, are hunted and preyed upon by various animals, including the crowned hawk-eagle, the African leopard, the common chimpanzee, and humans.

[7] Other forest residents, such as the yellow-casqued hornbill (in addition to other birds) and other primates, are able to discriminate between these and use them to take appropriate action, should a mutual threat be present in the immediate area.

A similar system is observed in India with the axis deer (or chital) on the ground and the Hanuman langur in the trees above them; the two species are seemingly inseparable, living in near-symbiosis as the forest’s carnivore "warning-system".

[9] Native tribes in the tropical forest of West Africa poach Diana monkeys, which are sold as luxury meat and seen as a commodity.