Pretreatment serum levels of the tumor-associated antigens CA-125, tissue polypeptide antigen (TPA), carcinoembryonic antigen (CEA), and placental alkaline phosphatase (PLAP) were analyzed in 142 patients with epithelial ovarian carcinoma, and related to clinical and histopathological parameters. In a linear multiple regression model CA-125 serum levels were profoundly influenced by the type of tumor, i.e., mucinous or nonmucinous. Clinical stage also had significant impact, whereas grade of differentiation did not, when the other two factors were taken into account. CEA levels were also dependent mainly on histological type. Mucinous tumor cases had high levels. Only clinical stage or tumor burden had a significant impact on TPA levels. PLAP levels were significantly influenced by histological type of tumor and by grade of differentiation but not by clinical stage. The dependence of CA-125 levels upon clinical stage was evident only in nonmucinous tumors. Furthermore, size of the primary tumor was not important for the CA-125 value, in contrast to FIGO stage. Thus CA-125 is primarily a sensitive indicator of disseminated disease in ovarian carcinoma patients. On the basis of the CA-125 level it was possible to predict the extent of disease with an overall accuracy of 55%. If TPA and CEA levels were also considered, the predictive accuracy was 63%.