During a 17-year-period from 1967 to 1983, 110 total cystectomies for transitional cell bladder cancer have been performed in our clinic. During the postcystectomy period, upper urinary tract urothelial cancer developed in seven patients (6.4%). In every case a multifocal, low stage transitional cell cancer had been found in the bladder. The time between the cystectomy and discovery of the upper tract tumour varied from less than three months to almost 13 years. In five cases the first sign of occurrence of the tumour was malignant conduit urine cytology, in two macroscopic haematuria with subsequent malignant cells in urine. In one patient bilateral renal pelvic tumours were found. Five patients could be surgically treated. The need for regular conduit urine cytological studies at short intervals in patients with multifocal low stage and high grade transitional cell carcinoma in the cystectomy specimen is emphasised.