Taenia solium cysticercosis is a frequent cause of neurological disease in developing countries. Specific diagnosis of cysticercosis is difficult. We obtained serum and/or CSF samples from 204 consecutive patients admitted to a neurological ward in Lima, Peru, and looked for antibodies specific for T solium with the enzyme-linked immunoelectrotransfer blot (EITB) assay. 21 (12%) of 173 serum samples from these patients were EITB-positive. In contrast, only 2 (1.5%) of 135 patients attending a public endoscopy clinic and 1 (1%) of 88 patients attending a private endoscopy clinic were seropositive. 1 (1%) of 98 pregnant women living in a Lima shanty town was EITB-positive. 15 (58%) of 26 neurology patients diagnosed clinically as having cysticercosis were seronegative. Routine screening by EITB of all patients with neurological symptoms from areas of endemic cysticercosis would avoid misdiagnosis of this common and treatable disease.