Transurethral external sphincterotomy was performed in 36 male and 2 female patients with obstructive symptoms. The patients were studied with synchronous pressure-flow-electromyography investigations. They all had hypoactive bladders without organic obstruction, as determined by urethroscopy, micturition urethrocystography, urethral pressure profile and sphincterometry. 11 patients had urinary retention. Sphincterotomy was done at the 12 o'clock position. Voiding improved in 33 (91%) of the 36 male patients. During the follow-up time, 7 patients were reoperated with altogether 15 sphincterotomies, most often within 3 months after the first sphincterotomy. Transurethral resection of the prostate was done in 4 patients, with resultant incontinence in one case. In one female patient several sphincterotomies as well as bladder neck resections provided only temporary improvement necessitating clean intermittent self-catheterization. External sphincterotomy is a suitable and effective method for male patients with functional urinary disorders without organic obstruction.