During the period 1987-1992, 99 patients with benign bladder tumours were followed regularly with transabdominal ultrasound of the bladder and out-patient flexible cystoscopy. Thirty-five patients had recurrent bladder tumours, but in only one case was there progression to invasive tumour. Seventy-six per cent of the recurrences were diagnosed by flexible cystoscopy while 22% were found by ultrasound. Compared to conventional follow-up programs with in-patient rigid cystoscopy the combination of ultrasound and flexible cystoscopy proved to be safe, highly acceptable by the patients and cost-effective.