Summary:Seven patients with active neurocysticercosis (NCC) received an eight days treatment with albendazole and were followed up using computed tomography (CT-scan) and a monoclonal antibody based ELISA for the detection of circulating antigen (Ag-ELISA). Only three patients were cured as was shown by CT-scan and by the disappearance of circulating antigens one month after treatment. After a second course of albendazole therapy, two other patients became seronegative. CT-scan showed the disappearance of viable cysts in all persons who became seronegative whereas patients who were not cured remained seropositive. These preliminary results show that this Ag-ELISA is a promising technique for monitoring the success of treatment of NCC patients because of the excellent correlation between the presence of circulating antigens and of viable brain cysts.