This study was designed to determine the effect of N-acetyl-cysteine (NAC, a natural hydroxyl radical scavenger) treatment on levels of pulmonary malondialdehyde (MDA, the end product of lipid peroxidation) and glutathione (GSH, a natural antioxidant) in thermally injured rats. Severe skin scald injury (30 percent TBSA) caused a significant decrease in GSH levels, and a significant increase in MDA levels in lung tissue both at 1 h and 1 day postburn injury. Treatment of rats with NAC (15 mg/kg intraperitoneally, 15 min and 12 h following the burn) significantly improved GSH levels, and decreased ongoing lipid peroxidation at 1 day. This study showed that thermal injury resulted in increased pulmonary lipid peroxidation, and this remote organ injury was decreased by treatment with NAC. In addition NAC, a scavenger of hydroxyl radicals, improved GSH levels in the lungs. The higher level of GSH in the lungs of the burned rats treated with NAC could be due to either a decrease in the rate of degradation of GSH or to an increase in its synthesis. No data about these possibilities are provided.