A case of adenomatous polyp occurring at a ureterocaecal anastomosis, 25 years after urinary diversion following a total cystectomy for carcinoma of the bladder, is reported. Bilateral nephrectomy for chronic pyelonephritis was carried out 25 years after the initial surgery and, following this, a sinus formed at the incision at the right loin. A sinogram showed contrast filling the right ureter and caecum, and outlined a lobulated filling defect at the ureterocaecal anastomosis. Subsequent histology revealed a dysplastic tubulovillous adenoma. The clinical presentation and management of tumours at the ureterointestinal junction are discussed.