Ten patients with advanced renal carcinoma were treated by ifosfamide (50-60 mg/kd/day x 5 days). The treatment was repeated every 4 weeks and continued until progression appeared. Two patients came into partial remission, two had subjective improvement, and six did not respond. Seven patients developed acute psychopathological symptoms during the first ifosfamide-cycle. Five patients had visual and paranoid hallucinations, four patients were completely confused. Follow-up for up to 10 weeks showed a persisting organic brain syndrome in five patients.