A 45 year old female who received radiotherapy for stage II-B uterine cervical cancer four and half years ago, presented with persistent hematuria due to radiation cystitis. 15 (S)-15-methyl prostaglandin F2-alpha (1 mg in 100 ml of normal saline) was instilled into the bladder daily for two days. The severity of bleeding decreased considerably. However, significant hematuria recurred 19 days later which continued despite bladder irrigation with normal saline. 1 mg of 15 (S) 15-Me PGF2 alpha mixed with hydroxyethyl cellulose gel to a volume of 10 ml was then instilled into the urinary bladder daily for three days and macroscopic hematuria ceased. Urinary frequency and urgency were the side effects which lasted for ten days. There has been no recurrence of macroscopic hematuria during the five months follow-up. In conclusion, 15 (S) 15-Me PGF2-alpha may be administered intravesically to control moderate hematuria due to radiation cystitis.