Chromatographic analysis of Fasciola gigantica adult crude extract was undertaken using Sephadex G-200. Four fractions were isolated by this approach. The isolated fractions showed simple electrophoretic profile, as judged by SDS-PAGE, compared to the complex profile of crude extract. Fraction 2(F2), exhibited the most potent activities against rabbits hyperimmune serum in ELISA. This fraction was utilized in diagnosis of fascioliasis among buffaloes recording 100% sensitivity. Structural characterization of the isolated fraction, F2, by SDS polyacrylamide gel electrophoresis, isoelectric focusing and amino acid analysis showed that F2 consists of only three polypeptides of 133 KD, 106 KD and 100 KD with isoelectric points of 7.2, 6.5, 5.9 and 5.2. Moreover, 17 amino acids were identified in F2 with high proportions of only three of them (Lysine, Alanine and Proline).