Ninety-three formalin-fixed, paraffin-embedded surgical specimens from 69 ovarian tumors representing all five epithelial cell types were studied by immunohistochemistry, peanut and ulex lectin binding, and carbohydrate histochemistry. Carcinoembryonic antigen (CEA) was mostly noticeable in mucinous tumors (21 of 26). Glycogen was highly prevalent in clear cell (8 of 9) and endometrioid (4 of 6) carcinomas, in contrast to serous carcinomas (3 of 6), where it was only focally distributed, and was completely absent in all mucinous tumors. Among the different types of malignant tumors examined, mucinous carcinomas most frequently contained neutral mucins (6 of 8). In mucinous tumors, an increase in CEA content and a decrease in the total mucin secretion, particularly the strongly acidic sulfated group, were found to parallel the increased malignant potential of the tumor. Peanut and/or ulex lectin binding was a feature common to almost all epithelial neoplasms. Although peanut lectin showed a slightly higher affinity to serous and clear cell tumors, while ulex lectin was bound more to mucinous and endometrioid neoplasms, distribution of D-galactose and L-fucose does not have a diagnostic utility in these tumors. Placental lactogen was detected in 3 of 17 benign tumors and one of 19 tumors of low malignant potential (LMP). The beta subunit of hCG was found in one of 17 benign tumors, in 2 of 19 LMP tumors, and in 3 of 31 carcinomas.