Human and porcine cases of neurocysticerosis were compared by computed tomography in regard to the morphological characteristics of the parasites and the impact of the infection on the brain. In pigs and young people many parasites were usually found, but this was seldom the case in adult humans. These parasites were small and located mainly in the parenchyma and the subarachnoid space; no calcified cysticerci were found. In contrast, in adult humans cysticerci were heterogeneous in appearance and distribution. The brain of the pigs showed no evidence of inflammatory reaction while young people had oedema, enhancement and hydrocephalus; in contrast, adults showed diverse tomographic characteristics of brain response. Thus, the disease has at least 2 different forms. It may be mild with short development and parasites of similar appearance, as occurs in young hosts. In contrast, a long lasting disease occurs in adults, with diverse tomographic, neurological and parasitological features.