Praziquantel is recommended as the drug of choice for all forms of schistosomiasis. We report the first case (to our knowledge) of exudative effusive polyserositis following treatment of schistosomiasis with this drug. This involved pleura, pericardium, and peritoneum and was associated with acute respiratory failure. The latter preceded the appearance of pleural effusions. We present a brief review of the literature and attract attention to the need for close observation of patients with schistosomiasis who are treated with praziquantel.