Five patients with severe postpartum hemorrhage due to uterine atony and unresponsive to oxytocin, ergonovine, and massage were treated with intramyometrial injection of 250 micrograms of prostaglandin (15S)-15-methyl PGF2 alpha-Tham. Four patients received 2 injections (500 micrograms), and 1 patient required 1 injection (250 micrograms). Three (60%) of 5 patients responded successfully with an increase in uterine tone and cessation of uterine hemorrhage, thus obviating the need for hysterectomy. Two patients had no uterine response, possibly because of delayed use of the drug, excessive blood loss, and accompanying shock; they required hysterectomy. Intramyometrial injection of prostaglandin is an effective and safe method of managing severe postpartum hemorrhage unresponsive to oxytocin and ergonovine, but it must be used early during the management of atony to obtain maximum effect. This method should precede surgical management of uterine atony.