Erythrocyte superoxide dismutase (SOD-1) activity and cerebrospinal fluid (CSF), blood plasma low-density lipoprotein (LDL) and erythrocyte thiobarbituric acid reactive substance (TBARS) concentrations were determined in 30 patients with brain contusion and in 37 control patients with low back pain due to noninflammatory degenerative lumbar disc disease. In comparison to controls, during 10-day follow-up patients with brain contusion had significantly increased erythrocyte SOD-1 activity and CSF, blood plasma (LDL), and erythrocyte TBARS concentrations. The highest CSF TBARS concentrations were observed in five patients who died 2, 7, or 8 days following head injury. A significant negative correlation was found between erythrocyte SOD-1 activity or TBARS concentrations, in the blood plasma LDL fraction and erythrocytes, and The Glasgow Coma Scale score. These results suggest that enhanced lipid peroxidation processes, which seem to correlate with the severity of head injury, accompany brain contusion.