Ten species of nonhuman primates in West African habitat were analysed for variolavaccinia subgroup haemagglutination-inhibition (HI) and neutralization antibodies. The animals were taken in 27 different sampling zones in parts of the Ivory Coast, Mali, and Upper Volta. Of the 195 tested, 15 (8%) had elevated HI antibodies after nonspecific reactions were reduced with potassium periodate pretreatment. Positive neutralization antibodies were found in 21% (44 of 206). Antibodies were detected in serum from monkeys living near two areas where monkeypox cases in humans had occurred. Four samples were tested for monkeypox specific antibodies using an indirect immunofluorescent test; 3 were positive. Despite the prevalence of poxvirus antibodies in monkeys (and other animals) in West Africa, smallpox eradication has been maintained in the area since 1970; thus, animal reservoirs of poxvirus appear to pose no threat to the worldwide smallpox eradication programme.