Single dose therapy with oral oxamniquine was given to 107 Saudi patients suffering from schistosomiasis due to Schistosoma mansoni and they were followed for a period of six months. Clinical cure judged by symptomatic improvement and negative stool counts for S. mansoni eggs was achieved in 88.8%. Side effects were minimal and reversible and it is concluded that this form of treatment is successful for the control of S. mansoni infection.