Most vesical neck contractures occur after resection of adenomas weighing less than 20 gm. This complication is believed to be secondary to excessive resection or fulguration of an undilated bladder neck. Prophylactic bladder neck incision was performed in conjunction with transurethral resection of the prostate on 114 patients with prostatic adenomas weighing less than 20 gm. Vesical neck contracture occurred in 1 patient (0.87 per cent), compared to 12 contractures in 161 patients who underwent transurethral resection of the prostate alone (7.5 per cent). Increasing bladder neck diameter by incision appears to be protective against formation of vesical neck contractures in patients with small obstructing prostatic adenomas.