The relative merits of cystoscopy alone and cystoscopy plus urethral dilatation were compared in a randomised study of women with recurrent frequency and dysuria. One hundred women were studied before and at least 6 months after operation. A detailed questionnaire was completed, the severity of the symptoms was scored and patients underwent urodynamic investigation. Forty-eight patients underwent cystoscopy alone and 52 underwent urethral dilatation. The two groups were well matched with regard to age, parity, menopausal status, previous gynaecological surgery and severity of symptoms. A significant improvement in symptoms was observed in both groups after treatment: 30% had no residual symptoms, 50% were improved and 20% were no better. However, no difference in final outcome was observed between those who had undergone cystoscopy alone and those who had undergone urethral dilatation. Furthermore, 7 patients who underwent urethral dilatation experienced transient stress incontinence of urine, a complication not observed in women who underwent cystoscopy alone. No benefit was observed from the addition of urethral dilatation to cystoscopy alone in women with recurrent frequency and dysuria.