A 55-year-old man was admitted to our hospital because of arthralgia, purpura, abdominal pain, melena and leg edema. Laboratory findings showed an increased serum creatinine level (2.4 mg/dL), hematuria and massive proteinuria (10.7 g/day). Renal biopsy revealed diffuse endocapillary proliferation and focal mesangial proliferation with IgA deposition predominantly in the glomerular capillary walls. Based on these findings, he was diagnosed as having Henoch-Schönlein purpura nephritis and steroid therapy was started. Following steroid therapy, his nephrotic state remained unchanged, although his renal function improved concomitantly with the disappearance of arthralgia, purpura and abdominal symptoms. Therefore, cyclosporine was added to the steroid therapy to enhance immunosuppression. However, melena recurred and anemia progressed. Endoscopy revealed multiple ulcers in the duodenum and jejunum, and clipping was performed at some bleeding sites. However, he died of hemorrhagic shock. The autopsy revealed that hemorrhagic lesions having cytomegalovirus infection spread widely in the stomach, duodenum and jejunum. Recurrence of gastrointestinal bleeding during the treatment of Henoch-Schönlein purpura nephritis is usually due to severe vasculitis or steroid ulcer. However, in patients receiving strong immunosuppressive therapy, cytomegalovirus infection needs to be considered as cause of gastrointestinal bleeding.