Sairei-to has been reported to inhibit granulation and fibroblast proliferation. We administered Sairei-to (9.0 g/day) to two 77-year-old men with repeated urethral stenosis after transurethral resection of prostate (TUR-P) and examined its clinical effects. Urethral stricture did not recur in these patients for 7 to 8 months. There were no side effects in these patients. Sairei-to is suggested to be useful to prevent recurrence of urethral stricture after a transurethral procedure.