A histopathological study of 15 cases of cerebral schistosomiasis mansoni is presented. All patients had the hepatosplenic form, and except for two, the cardiopulmonary form of the disease. The most common lesions were periovular mononuclear inflammatory reaction, granulomas and focal astrocytosis. Arteritis and vascular lesions suggesting sequelae of arteritis or ova passage through the arterial wall were found in 26.7% and 20% of the cases, respectively. The clinical features and the possible mechanisms by which the S. mansoni ova produce the vascular changes are discussed. These findings indicate that vascular changes were common in our patients with cerebral schistosomiasis mansoni.