The occurrence of upper urinary tract tumors has been studied in 479 patients followed for bladder cancer: The incidence rate is low (2.9%) but increases with time (mean: 58 months). Some patients are more exposed: those who underwent repeated transurethral resections of Ta-T1 multifocal bladder carcinoma. Retrograde and voiding cystourethrogram seems to be useful to select a group "at risk" during the follow-up of patients with bladder tumors treated by endoscopic resection: a yearly excretory urography for upper urinary tract survey should then be performed.