ABSTRACT
The prevalence of schistosomiasis in Demooh, Dakahlia [in Nile Delia] in winter 1990 was 19.89% among the studied group of children [1367] aged from 5 to 15 years. The prevalence rate of S. mansoni was 17.84% and only 2.05% for S. haematobium. By using egg counting, 93.4% of the studied group were found to have light and moderate infections. The most affected age group was found to be from 12 to < 14 years of age in both bilharzial types. Infections among males was 2.6 times than in females in both bilharzial types. The effect of one dose of praziquantel on treatment of a sample of cases [145 child] was 100% cure rate for S. haematobium and 92 .25%. For S. mansoni, persistance in these few cases may be due to heavy infection or reexposure to infected water after treatment, there no sex difference in the cure rate. The most important side effects of the drug as reported by patients were, dizziness, abdominal pain and headache which were transient and disappeared after few hours