The African Programme for Onchocerciasis Control (APOC) has put in place a study to assess the long-term impact of the community-directed treatments with ivermectin on various clinical and entomological indicators of onchocerciasis. As the results obtained would depend on community participation in the treatments, surveys were also conducted at the study sites to assess the people's knowledge, attitudes and practices regarding onchocerciasis and its treatment. This article presents the anthropological observations made before the implementation of the treatments in three sites: one in the Central African Republic, and two in the Democratic Republic of Congo. The information collected shows that the populations have a relatively poor knowledge of the manifestations and mode of transmission of onchocerciasis. The communities' attitudes towards those individuals afflicted with the disease vary from one site to another. Regarding treatment, the populations use both traditional and 'modern' treatments, but the beneficial effects of ivermectin are not well known. The differences recorded between the sites surveyed demonstrate that the messages to be delivered to the populations before the distributions should take into account the local epidemiological and socio-anthropological context.