We report a case of ileal perforation caused by cytomegalovirus (CMV) infection in a patient with peritoneal recurrence of gastric cancer. Emergency laparotomy revealed a pinhole-sized perforation in a reddish segment of the small bowel, 100 cm proximal to the terminal ileum, and peritoneal carcinosis of recurrent gastric cancer invading the transverse colon and the gastrojejunal anastomosis of a Billroth-II procedure. The affected ileum was resected, a primary anastomosis was performed, and a colostomy was made in the ascending colon. The histology of the ileum revealed acute inflammation with vasculitis and CMV inclusions in the macrophages and endothelial cells and evidence of CMV on immunostaining. There was no evidence of cancer cell invasion or any other pathogens. Although the prognosis associated with bowel perforation due to CMV infection is poor, emergency surgery saved our patient's life.