A survey on filariasis was conducted in the south-western part of the Adamaoua Province (Cameroon). In the Bankim district, located in the Tikar plain, the 10 surveyed villages were all hyperendemic for loiasis. The prevalence of microfilaraemia in adults exceeded 50% in four communities, and 5.4% of the adults had microfilarial loads above 30,000 microfilariae per ml blood. In the Banyo district, which is contiguous but located on the Adamaoua Plateau, five of the six villages examined were hypoendemic for loiasis. The considerable levels of endemicity recorded in the Tikar Plain, a region of pre-forest shrub savanna, are probably due to the presence of forest-galleries, favourable to the biology of Chrysops. Regarding onchocerciasis, the most affected villages were located south of the Tikar Plain, near the Mbam River. The low prevalence of hydroceles suggests that lymphatic filariasis is not endemic in this study area.