A 58-year-old normotensive male with normal renal function and gastric cancer underwent total gastrectomy and received adjuvant chemotherapy with mitomycin C (MMC) for 10 months. He developed anemia, hypertension, and renal function impairment 9 months after initiation of chemotherapy. Kidney biopsy showed thrombotic microangiopathy with marked mesangiolysis and expansion of the subendothelial space resulting in cystic dilation of the glomerular capillaries, and cellular atypia in the tubular cells. His renal function deteriorated gradually then stabilized after treatment with plasma exchange, antihypertensive agents, and antiplatelet agents. He had no sign of tumor recurrence after 3 years of follow-up. We suggest that patients receiving MMC should have their blood pressure and renal function closely monitored for the possibility of development of drug-induced renal insufficiency.