Partially purified Fasciola gigantica worm antigens were evaluated in an enzyme-linked immunosorbent assay (ELISA) for the specific serological diagnosis of fascioliasis. The diagnostic potential of 10 antigen fractions derived from gel-filtration peaks (II & III) were evaluated individually or in combination against a panel of admission sera obtained from 50 patients subsequently diagnosed as having a variety of systemic parasitic diseases, and from 10 healthy volunteers with no recent history of parasitic infections. Fractions 2 and 10 were highly specific for Fasciola infection and failed to react with sera from any patient with other parasitic diseases or from controls. All other fractions exhibited reactivity with the majority of sera from the fascioliasis patients, but also with some sera from patients infected with other parasites. Based on these results, the ELISA, as outlined here, should be considered as a rapid and specific technique for the diagnosis of fascioliasis and also as an epidemiological surveillance technique in areas endemic for F. gigantica infection.