The wide clinical spectrum of neurocysticercosis has led to many attempts at clinical, radiological, CSF and other classifications. Based on an objective review of the relevant literature and on a prospective study of 42 patients with active neurocysticercosis, a new classification is proposed, based on clinical, tomographic, magnetic resonance and CSF evidence of viability of cysts. The first step is to define whether the disease is active or not. Inactive disease may be parenchymal calcifications or hydrocephalus. Active disease may be intraparenchymal, extraparenchymal or mixed. Statistical analysis of 42 cases with active disease shows intraparenchymal disease to occur in younger patients, perhaps more frequently in females, and to have a better prognosis than extraparenchymal of mixed disease. The latter appears to have the worst prognosis. Therapeutic implications are that only active disease warrants etiological therapy. There remain doubts about the best therapy for some infrequent subtypes of extraparenchymal and mixed disease.