We herein present a case of pneumatosis cystoides intestinalis. A 56-year-old woman was admitted to Nagasaki Prefectural Shimabara Hospital with diffuse and mild abdominal pain. A plain abdominal X-ray revealed free air in the right subphrenic space, and computed tomography showed an extraluminal gas-filled lesion adjacent to the small intestine. With a tentative diagnosis of perforation of the small intestine, a laparotomy was performed, although she had little tenderness and no rigidity on physical examination. Upon opening the peritoneal cavity, multiple bullae-like cysts were noted on approximately one meter of the ileal serosa; however, no site of perforation was detected. Removal of the portion of what appeared to be the affected bowel was the procedure of choice. The resected specimens histologically showed pneumatosis cystoides intestinalis without any perforation. Her postoperative course was uneventful and she has been doing well with no evidence of recurrence as of the end of June 2005.