Abstract Aim: The aim of the study was to evaluate IL-10 and TGF-beta levels in the peritoneal fluid (PF) and plasma of patients with ovarian cancer (n=104), serous cyst (n=32) or normal controls (n=20). IL-10 and TGF-beta levels were correlated to myeloid (M) and lymphoid (L) dendritic cells (DC). Material and Methods: IL-10 and TGF-beta concentrations were evaluated using the enzyme linked immunosorbent assay (ELISA). The percentage of DC in mononuclear cells was quantified by using flow cytometry. Results: The PF and plasma IL-10 concentrations were significantly higher in epithelial ovarian cancer (EOC) patients when compared to the women with serous cyst (the reference group). Plasma levels of IL-10 were elevated in EOC patients in comparison with the reference and control groups. There were significant differences in the PF and plasma IL-10 levels with respect to tumor stage, grade and histology. Significant negative correlations were found between the plasma IL-10 levels, MDC and LDC in the peripheral blood. TGF-beta levels were detected in PF of all EOC patients and were significantly lower when compared with plasma. Plasma levels of TGF-beta were elevated in EOC patients compared with the control group. No significant differences in the PF and plasma TGF-beta levels were noted between EOC patients and the reference group. The authors did not find a correlation between the plasma and PF TGF-beta levels and the percentage of MDC and LDC. Conclusions: IL-10 production in EOC patients depends on the tumor stage, grade and histological type of the tumor cells. IL-10 may have impact on the percentage of dendritic cells in EOC patients.