An imbalance of oxidative-antioxidant defence mechanism has been proposed in systemic lupus erythematosus patients. Co-administration of N-acetylcysteine (NAC) which has a strong antioxidant activity may produce a satisfactory therapeutic outcome when added to standard therapy. We report a case of a 46-year-old lupus nephritis patient who received 1800 mg of NAC orally. After NAC, this patient showed a higher glutathione level, and a normal level of malondialdehyde, a lipid peroxidation product. In addition, the urinary protein levels, the complete blood counts and physical examination of the affected organs showed improvement. However, a well-controlled trial is needed to confirm the value of high-dose NAC in lupus nephritis patients.