One hundred and three male and female children of 6 to 14 years old with onchocerciasis, having or not ocular involvement and a mean skin microfilariae level of 36.1 mf/mg, received, in October 1986, a single oral dose of 150 mcg/kg ivermectin and controlled at day 4, 3 months, 6 months and 12 months post treatment. After the last control they were retreated with the same dose. The skin microfilariae count fell down to 94% of the initial level at day 4 and to 99% at 3 months. At 6 months the microfilariae count was 2% of the initial level and 5% at 12 months. The percentage of patients having microfilariae in the anterior chamber of the eye which was 33% before treatment fell down to 6% at 12 months. The percentage of patients having microfilariae in the cornea was 39% before treatment and 18% at 12 months. In the cornea and anterior chamber there was a very reduced number of microfilariae still present. 65% of the children had lesions of keratitis before treatment and 34% two months later. Adverse effects (fever, headache, pruritus, oedemas, myalgias, arthralgias) occurred in 64% of children after the first treatment and 50% after the second. They were of weak or moderate intensity and receded rapidly after administration of aspirin and/or anti-histaminic. The administration of ivermectin is an efficient and well tolerated drug in children above 5 years old.