Over a three-year period, 646 sera from 630 patients with signs and symptoms compatible with neurocysticercosis were investigated for antibodies to cysticercal antigens using an ELISA test. Overall, 12 pc specimens were positive. The sensitivity of the ELISA, when compared with a limited number of computerised tomography investigations, was over 70 pc. False negative serology was associated with HIV infection in some patients. The positive predictive value was 87 pc and the negative predictive value was 85 pc when patients with active infection, potentially amenable to chemotherapy, were considered. The specificity, determined from serological tests of patients with a variety of trematode, cestode and other infections, was over 90 pc. Three of 11 patients with intestinal taeniasis, and each of two patients with hydatid disease were seropositive. The results suggest the value of ELISA serology as a more cost-effective diagnostic method for all patients with suspected cysticercosis.