Oxamniquine in capsules was used in the treatment of 132 patients with chronic Schistosoma mansoni infections. 129 having the hepato intestinal form and 3 the hepato splenic form. The dose was 10mg per kiio body weight in 34 patients, 12.5mg in 35 and 15mg ip 63. The tolerance was excellent in 43.2% of those treated, good in 48.5% and satisfactory in 8.3%. The most frequent complaints were dizziness and somnolence which appear soon after ingestion and was transitory. Laboratory investigations showed in a few patients bromosutphalein retention, raised transaminases or biiirubin but insufficient to constitute hepatoxicity. The follow-up of the patients continued for more than 4 months and consisted of five or more examinations by a sedimentation method. AH the examinations were negative in 20 (66.66%) patients who took lOmg, in 13 (56.52%) who took 12.5mg and in 41 (89.13%) who took 15mg. Excluding children of iess than 16 years the cure rate rises to 95% among patients treated with 15mg.