In 21 women undergoing simultaneous urethrocystometry because of dysuria, urge, and difficulties to empty the bladder, the effects of prostaglandin E2 (PGE2) applied locally in the bladder and urethra were investigated. In all 9 patients receiving PGE2 intravesically, the bladder pressure increased. Simultaneously, there was a signficant decrease in maximum urethral pressure (p less than 0.05), and in urethral closure pressure (p less than 0.005). Residual urine decreased in the 4 patients, in whom it exceeded 50 ml before administration. All 12 patients receiving PGE2 intraurethrally showed a decrease in maximum urethral pressure). There was a significant increase in bladder pressure (p less than 0.05); urethral closure pressure decreased in all patients. Bladder capacity decreased significantly (p less than 0.01). Residual urine exceeding 50 ml was found in 6 patients; it decreased in 4 after PGE2 administration. It is concluded that PGE2 applied intraurethrally can decrease the intraurethral pressure and increase the bladder pressure without side effects. By these actions, the drug might be useful for facilitating bladder emptying in patients with acute retention of urine.