Data from experimental and clinical research suggest that sex hormones may influence the autoimmune process in multiple sclerosis (MS). Studies on the hormonal profile of patients with MS and its relation to the disease activity provide heterogeneous results. OBJECTIVE The aim of this study is to investigate the changes in serum levels of estradiol and progesterone and their correlations with the cytokine profile and the degree of disability in women with relapsing-remitting MS (RRMS). METHODS The serum concentrations of estradiol, progesterone, tumor necrosis factor-alpha (TNF-alpha), interferon-gamma (IFN-gamma), interleukine-4 (IL-4) and interleukine-10 (IL-10) were measured and the degree of disability was determined in 35 women with RRMS, during relapse and remission. Serum levels of hormones were measured by micro-particle enzyme immunoassay and ELISA was used for the cytokines concentrations. The degree of disability was assessed by the Expanded Disability Status Scale and the Scripps Neurological Rating Scale. RESULTS Sixty per cent of patients had serum concentrations of estradiol and/or progesterone below the lower limit of normal in one or both phases of MS. Hormonal levels increased significantly during remission in these patients. Women with and without hormonal abnormalities differed in terms of cytokine profile during relapse and remission. Significantly higher TNF-alpha in both phases and IFN-gamma in remission was found for the patients with hormonal disturbances compared to these with normal hormonal status. CONCLUSIONS Our study finds high frequency of hormonal disturbances among female patients with RRMS. Abnormally low concentrations of sex hormones are associated with higher serum levels of TNF-alpha and IFN-gamma, which could suggest suppressive effect of estradiol and progesterone on pro-inflammatory cytokine secretion.