Estrogen treatment has been found to be protective in experimental autoimmune encephalomyelitis (EAE) and possibly multiple sclerosis (MS). We investigated whether the effect of estrogen treatment is gender-specific. Estrogen receptor (ER) expressions, ERalpha and ERbeta, were found to be equivalent in both genders. EAE disease severity in both females and males was decreased with estriol treatment as compared to placebo. Finally, proinflammatory cytokine production during autoantigen-specific immune responses was decreased with estriol treatment in both females and males. These data support a potential role for estriol treatment for men in addition to women with MS.