Three patients developed veno-occlusive disease of the liver (VOD) after allogeneic stem cell transplantation. On the day after diagnosis, N-acetylcysteine (NAC) was given, initially in loading doses and thereafter 50-150 mg/kg/day for 12 to 31 days. The maximum bilirubin levels were 137, 58 and 138 mmol/l in the three patients, respectively. After the introduction of NAC, bilirubin, aspartate aminotransferase, sIL-2 receptor and IL-8 decreased. All three patients achieved normal bilirubin levels and prothrombin times. To conclude, NAC may be useful for treatment of VOD.