The psychostimulant drug modafinil has been used for many years for the treatment of sleep disorders. Recent studies have indicated that modafinil has immunomodulatory properties in the central nervous system (CNS) and peripheral immune cells. Thus, our aim was to determine the effects of in vivo therapeutic treatment with modafinil on the severity of clinical symptoms and immune response during the acute phase of experimental autoimmune encephalomyelitis (EAE), an experimental model of multiple sclerosis. Modafinil treatment, given after the onset of symptoms, resulted in an improvement of EAE symptoms and motor impairment, which was correlated with reduced cellular infiltrate and a decreased percentage of T helper (Th) 1 cells in the CNS. The spinal cord analysis revealed that modafinil treatment decreased interferon (IFN)-y and interleukin (IL)-6 protein levels and down regulated genes related to Th1 immunity, such as IFN-gamma and TBX21, without affecting Th17-related genes. Our research indicates that therapeutic modafinil treatment has anti-inflammatory properties in an EAE model by inhibiting brain Th1 response, and may be useful as adjuvant treatment for multiple sclerosis.