It is the specific treatment of mansoni schistosomiasis that aims to act directed on the parasite, through chemotherapy. Constitutes fundamental indication to the treatment of schistosomiasis active forms, that is, these determined by the presence of living eggs in the feces or in material from rectal biopsy, since eventual contra indications are respected. Two are the medicaments actually used: oxamniquine, used in the single dosage of 15 mg/kg, V.O. for adults and 20 mg/kg V.O. for children divided in two doses, offers a percentage of 30 to 40% of cures, evaluated by quantitative "oogram" and praziquantel, in the single dose of 60 mg/kg V.O., presents a cure index of 30%, however in sequential doses, of 60 mg/kg during 3 days or 30 mg/kg, 6 days, cure percentage is elevated to 95%, evaluated by oogram. The evaluation of the treatment by quantitative or qualitative examination methods does not show the same sensibility. The percentage of cure according to feces examination, the quantitative of Kato-Katz or the qualitative (sedimentation), showed indexes from 90 to 100%, for either one of the drugs, even in single dose, which evidences the difference of methodology of therapeutic evaluation. Tolerance to both medicaments is from good to regular, with collateral effects in 30 to 40% of the patients.