The diagnostic value of computed tomography (CT) was assessed in 44 patients with alveolar or cystic echinococcosis. CT examination was concentrated mainly on the liver, which was involved in all patients, and was extended to lung, intra or retroperitoneal space, bone and brain if necessary. The CT image of the liver in cystic echinococcosis was often characteristic. It showed sharply outlined masses with attenuation values similar to water. Internal structures were caused by daughter cysts. Typical marginal calcium deposits indicated regression changes in the host membrane. In all cases with alveolar echinococcosis an indistinct solid mass was found, often with central necrotic colliquation and plaque-like calcifications within the tumor.