As a disease with many unknown details in etiology and pathogenesis, and treatment with limited efficiency Multiple sclerosis still remains in the focus of the scientific interest. The incidence of MS is increasing worldwide and in women more than in men with the female:male ratio now approaching 4:1 The present book contains an extensive overview of the recent findings about the role of the female sex hormones and cytokines in the pathogenesis and course of MS and the results of author`s own study on the profile of female sex steroids and cytokine serum concentrations in women with relapsing-remitting MS. Very interesting data about the dynamics of the investigated parameters in different clinical phases of the disease and their correlations with the degree of disability are discussed in the context of immunomodulatory effects of estrogenes and progesterone.