Because oxidative damage has been known to be involved in inflammatory and autoimmune-mediated tissue destruction, modulation of oxygen free radical production represents a new approach to the treatment of inflammatory and autoimmune diseases. Central nervous system tissue is particularly vulnerable to oxidative damage, suggesting that oxidation plays an important role in the pathogenesis of multiple sclerosis (MS) and its animal model, experimental autoimmune encephalomyelitis (EAE). Caffeic acid phenethyl ester (CAPE), an active component of honeybee propolis, has been determined to have antioxidant, anti-inflammatory, antiviral, and anticancer activities. We have previously reported that CAPE inhibits ischemia-reperfusion injury and oxidative stress in rabbit spinal cord tissue. The present study, therefore, examined effects of CAPE on oxidative tissue damage in EAE in rats. Treatment with CAPE significantly inhibited reactive oxygen species (ROS) production induced by EAE, and ameliorated clinical symptoms in rats. These results suggest that CAPE may exert its anti-inflammatory effect by inhibiting ROS production at the transcriptional level through the suppression of nuclear factor kappaB activation, and by directly inhibiting the catalytic activity of inducible nitric oxide synthase. (C) 2004 Elsevier Inc. All rights reserved.