We investigated plasma levels of selected hematopoietic cytokines: stem cell factor (SCF), granulocyte-macrophage colony-stimulating factor (GM-CSF), granulocyte colony-stimulating factor (G-CSF), and macrophage colony-stimulating factor (M-CSF) and the tumor marker cancer antigen (CA 125) in epithelial ovarian cancer patients as compared with control groups: benign ovarian tumor patients (cysts) and healthy subjects. Cytokine levels were determined by enzyme-linked immunosorbent assay, CA 125 - using the chemiluminescent microparticle immunoassay method. Our results have demonstrated significant differences in the concentrations of M-CSF, G-CSF, SCF (with the exception of GM-CSF), and CA 125 between the groups of ovarian cancer patients, cysts patients, and the healthy controls. When compared with CA 125, M-CSF has equal or higher values of diagnostic sensitivity and specificity. The M-CSF area under the receiver-operating characteristic curve (AUC) was the largest from all the cytokines tested and slightly lower than the AUC of CA 125. These findings suggest the usefulness of M-CSF in diagnosing ovarian cancer, especially when discriminating between cancer and non-carcinoma lesions.