A precondition for the early diagnosis of ovarian cancer by means of raised tumour marker levels is high sensitivity at an early stage of the disease. In this study the relationship of the levels of the tumour marker CA-125 to the variables age, grading and histological status was examined in 52 patients with verified FIGO stage I epithelial ovarian cancer. A liminal value of 35 U/ml was accepted and the patients were split into 2 groups according to whether the tumour marker exceeded this value or not. The survival probability was calculated for each group in order to gauge the prognostic significance of this serum marker. Although there was no statistically significant correlation between the CA-125 levels established preoperatively and the above-mentioned variables, in contrast to other studies we found a higher overall sensitivity of 62%. Of particular interest is the considerably higher sensitivity of CA-125 in the postmenopausal patients within our collective. The findings of this study suggest that marker-positive patients might have a poorer survival prognosis.