Oxidative pathomechanisms play an important role in neurodegenerative diseases like Alzheimer's disease (AD). It has been shown that lipid peroxidation in cerebrospinal fluid (CSF) and plasma is increased in AD. To assess the role of oxidative stress in Creutzfeldt-Jakob disease (CJD), we investigated the oxidizability of lipids, the lipid composition and the levels of the antioxidants ascorbate and alpha-tocopherol in CSF and plasma of 15 CJD patients and 12 neurologically healthy controls. CSF and plasma lipid peroxidation was increased in CJD patients and polyunsaturated fatty acids were reduced in CSF of these patients. Ascorbate levels were lower in CSF and plasma of CJD patients, while alpha-tocopherol was found to be decreased in CSF but not in plasma. These results support the hypothesis that oxidative mechanisms are involved in the pathogenesis of CJD and provide a rationale for the use of antioxidants in the therapy of this disease.