Serum samples from patients with benign or malignant diseases were measured for the newly developed tumor markers CA54/61 and CA602 with the respective EIA kits for assessment of their utility as tumor markers. A total of 5236 patients were entered into the study, consisting of ovarian cancer patients, those with other cancers, pregnant women, and healthy volunteers. The CA54/61-positive rate with a cut-off value of 12 U/ml was 61.2% for ovarian cancers (50.4% with a cut-off value of 20 U/ml). A positive rate of 75.0% (64.4%) was achieved for mucinous cystadenocarcinoma, which was high, compared with that for CA125. On the other hand, the false-positive rate was 12.2%(5.9%) for benign ovarian tumors, and as low as 18.5%(8.7%) for endometriosis. The CA602-positive rate with a cut-off value of 63 U/ml was as high as 76.0% for ovarian cancers (69.8% with a cut-off value of 90 U/ml). On the other hand, the false-positive rate was relatively high at 21.9% (12.6%) for benign ovarian tumors, and 56.7% (40.0%) for endometriosis. These positive rates were therefore similar to those for CA 125. The levels of both CA54/61 and CA602 antigens well reflected the postoperative prognosis. These results suggest the utility of CA54/61 and CA 602 as tumor markers of ovarian cancers.