Background: Improvements in the surgical technique of radical prostatectomy have allowed the length of postoperative catheterization to be reduced dramatically over the past 20 years. Today, many surgeons perform a cystogram to ensure the anastomosis is watertight before an 'early' (day 7 or less) trial of void (TOV). We aim to show that achieving an intraoperative watertight anastomosis may preclude the need for routine cystogram prior to TOV. Methods: Between 31 May 1999 and 29 February 2004, we performed a prospective study of 68 consecutive patients who underwent radical prostatectomy by a single surgeon. We tested the vesicourethral anastomosis for watertightness intraoperatively by instilling 250 mL of normal saline in to the bladder and compared this with evidence of extravasation on the cystogram on day 7.Results: Fifty-four (79.4%) of the 68 patients had a watertight anastomosis intraoperatively. All men had a cystogram on day 7 (6-9 days). Sixty (88.2%) of these cystograms showed no evidence of extravasation. Three men (4.4%) who had evidence of a leak on their cystogram had achieved a watertight anastomosis intraoperatively. However, one of these men had suffered a postoperative septicaemia which may have jeopardized the anastomosis. Only two (2.9%) of the 68 patients had unsuspected extravasation at their day 7 cystogram. Therefore, 97.1% of patients (95% Confidence Interval: 95.1%-99.2%) could be suitably managed by our proposed protocol.Conclusion: Achieving an intraoperative watertight anastomosis is a very good predictor of a watertight cystogram on day 7. It seems feasible to avoid routine cystograms prior to TOV in the absence of other postoperative complications.