A 70-year-old man was admitted to a hospital with sustained pain in the hypogastric region of his abdomen. He had a history of left nephroureterectomy for bladder cancer at 46 years of age and total cystectomy and ileal neobladder reconstruction for recurrence of the cancer at 54 years of age. Abdominal computed tomography revealed a sac-like dilatation of the functional end-to-end anastomotic site of the ileum, containing stagnant intestinal contents. The patient was diagnosed with blind loop syndrome, specifically categorized as the blind pouch type. Abdominal pain persisted, and an urgent operation was performed 3 days after admission, owing to the high risk of intestinal perforation. Although the dilated anastomotic region was not perforated, the anastomotic site was resected and reconstructed by layer-tolayer anastomosis. To date, no recurrence has been observed. Blind loop syndrome of the functional end-to-end anastomotic site is rare. This condition should be considered a possible complication of functional end-to-end intestinal anastomosis, and surgical treatment is necessary in patients presenting with abdominal symptoms.