Human African trypanosomiasis (sleeping sickness) caused by Trypanosoma gambiense is recrudescing alarmingly in the Ivory Coast. Between 1987 and 1992, 980 new cases were registered. In the Bouafle District alone, 214 new cases were diagnosed in 1992, with a prevalence reaching 7% in some villages. This situation is a consequence of the neglect of control activities over the last five years. The problems linked with treatment of sleeping sickness in 626 patients, using three drugs, are described. The side-effects vary in severity according to the drug used. Out of 350 patients treated with melarsoprol (ARSOBAL), 4% developed encephalopathy, 5.7% died during treatment, 2% of encephalopathy. Relapses were noted in 3.7% of patients between 3 and 20 months after treatment. Among 150 patients treated with pentamidine, one case of diabetes mellitus was observed. The patient died of this complication 24 months after treatment. 2% relapses or reinfections were registered after pentamidine treatment. The most frequently encountered side-effects during intravenous plus oral treatment with DFMO were diarrhoea (64.4%) and anemia (35.5%). This drug was just as effective and better tolerated when treatment was limited to 14 days and administered intravenously only.