With the introduction of Praziquantel a highly effective anthelminticum against trematodes and cestodes has become available. After antischistosomal therapy with Praziquantel reduction of parasitic egg excretion occurs rapidly and lasts for at least one year under conditions with a low risk of reinfection. Patients treated with Praziquantel predominantly excrete non-viable eggs and therefore hardly contribute to a further transmission of the disease. Besides this parasitological improvement proteinuria, erythrocyturia, leukocyturia, and previously pathological lesions of the urinary tract as shown ultrasonographically more or less disappear. Praziquantel can therefore at present be considered the drug of choice in the treatment of schistosomiasis.