Clinical trials with Hycanthone were performed on forty-six patients with active Schistosomiasis mansoni (40 with hepatointestinal form and 6 with bsnign hepatosplenic involvement) hospitalized in Clinica of Tropical and Infectious Diseases of University of Pernambuco, Brazil. The drug was administered in a single intramuscular dose of 2,5 mg per Kg of body weight, and the tolerance was considered good despite of one patient who developed mild jaundice. The parasitological cure rate obtained was 95,65% (44 patients), and the AA. concluded that the drug is highly effective against Schistosoma mansoni infection.