The purpose of the present study was to evaluate multiplex liquid assay-based measurement of multiple ovarian cancer-associated biomarkers such as hemoglobin, haptoglobin and apolipoprotein E, together with CA125, which has been widely used in the diagnosis of ovarian cancer, in order to provide a higher diagnostic power. We measured the serum levels of CA125, hemoglobin, haptoglobin and apolipoprotein E from the serum of 76 healthy individuals and 69 ovarian cancer patients using a multiplex liquid assay system, Luminex 100. The results were analyzed according to normal versus ovarian cancer, tumor stages and tumor histology. In addition, to validate the use of these biomarkers for the diagnosis of ovarian cancer, the sensitivity and specificity of each biomarker was analyzed by its receiver operating characteristics (ROC) curve. The serum levels of all four biomarkers in ovarian cancer patients were significantly higher than those of healthy individuals. When CA125 was combined with the biomarkers, the overall sensitivity and specificity were significantly improved in the ROC curve, which showed 95 and 75% sensitivity and specificity, respectively. At 95% specificity for all stages the sensitivity increased to 75% compared to 41% for CA125 alone. For stage I+II increased the sensitivity to 68% from 36% for CA125 alone. For stage III+IV the corresponding values were 100 and 95%, respectively. Taken together, the new combination of hemoglobin, haptoglobin and apolipoprotein E with CA125 significantly improved both the sensitivity and the specificity of ovarian cancer diagnosis compared with those of individual biomarkers. These findings suggest the benefit of the combination of these markers for the diagnosis of ovarian cancer.