CA125, a coelomic epithelium-related antigen, is expressed in both normal and pathological conditions. In this study, we compared the glycosylation of CA125 antigen from amniotic fluid and the ovarian carcinoma cell line OVCAR-3, in order to detect possible differences as a specific marker of their origin. Antigens from both sources were radiolabelled and subsequently subjected to the affinity chromatography, using plant lectins differing in carbohydrate specificity as ligands. A common chromatographic scheme was applied to all columns, ie they were eluted with: a) washing buffer to wash out non-bound and low-affinity bound fractions, b) a solution of inhibitory sugar and c) a low pH buffer, to release the high affinity bound fractions. CA125 antigen from each source was found to be heterogeneous in respect to the existence of multiple glycoforms, with O-linked glycan chains predominating. However, the binding patterns of both N-and O-linked glycan-reactive lectins indicated distinct differences in carbohydrate composition between CA125 antigen isolated from amniotic fluid and OVCAR-3 cell line. The observed specificites of CA125-oligosaccharide chains might be of special importance from the biomedical aspect, in terms of their possible use for clinical evaluation of gynecological functions in health and disease.