The protocols for treatment of human African trypanosomiasis (sleeping sickness) with the organoarsenical drug melarsoprol are based on empirical observations. Therapy is often accompanied by serious side effects and relapses. Additionally, the duration of treatment, which is up to forty days, is a major drawback in African countries. Based on pharmacokinetic investigations an alternative therapy protocol for T. gambiense sleeping sickness has recently been proposed which consists of ten consecutive injections of 2.2 mg/kg melarsoprol given at intervals of 24 hours. In a preliminary study, eleven patients were treated in Vanga, Zaire following this alternative protocol which reduces the duration of the treatment to ten days. The results indicate that the alternative schedule was as effective as the traditional protocol, showed similar adverse reactions but required a much shorter treatment period.