The concentration of the turnor markera CA 125 and CA 15-3 in serum of patients with ovarian tumors was quantitated to test if there is a diacrimination between benign and malignant ovariam tumors. In the study of 96 patients, 76 benign ovarian tumniors and 20 malignant ovarian tummors, the sensitivity of the preoperatiue serurn CA 125 level (>35U/ml) in cletezting malignant tumor was 75%, spicificity 78%, positive predictive value 47% engative predictive value 92%, diagnostic efficacy 77%. The sensitivit,y of the preopratiue aerum CA 15-3 level (>20U/ml) was 30%, specilicity 99%, positive prdictive value 86%, negative prodictive value 84%, deagnostic value 84%. In the elevation of CA 125 alone and both Ca 125 and 15-3 concentration, the positivity and false positivity were 70%,11% and 25%, 1% in the doagnosis of malignant ovarian tumor respectuvely. Therefore our results suggest that additional measurement of CA 15-3 is more helful than measure ment of CA 125 alone in descriminating benign from malignant ovarian tumors by increasing the specificity.