A discriminant technique was applied to the different serological patterns obtained by enzyme-linked immunoelectrotransfer blotting (EITB) and by conventional immunological tests, in order to differentiate the residual antibody patterns present in healed hydatidosis from the ones present in patients with active hydatidosis. For this purpose, specific antibodies against Echinococcus granulosus were detected by indirect hemagglutination, agglutination of latex particles, basophil degranulation, and EITB for 23 patients with active hydatidosis and 45 patients with surgically cured hydatidosis. Discriminant analysis of the different serological patterns obtained by EITB and conventional serology correctly classified 92.54% of patients (93.3% if the patients are differentiated according to the time elapsed since surgery). This method detected the presence of active hydatidosis in 95.6% of patients for whom abdominal ultrasonography had confirmed the presence of active hydatid cysts. The global specificity was 88.9%. The specificity was 97.1% for patients who had been operated on 3 years ago or more and 63.6% for patients with less time since surgery.