Malignant mesothelioma is of special intei est because ol its known induction by exposure to ssbestos. To study this rare tumor in childhood, review was made of 42,597 death certificates for children who died of cancer in the United States, 1960-1968; 31 had a diagnosis of mesothelioma. Of these, 13 were confirmed by data from hospital records; the remainder had either been erroneously recorded or were unavailable for review. The illness characteristically presented with acute pleural effusion and encasement of the lung by tumor, with survival usually of less than 6 months. The case histories had no information on environmental exposures. To determine if the etiology of the neoplasm in childhood is similar to that in later life, better environmental histories must be obtained by alert practitioners.