Seventy-eight patients were treated with intravesical instillation of Thio-Tepa in an attempt to prevent postoperative recurrences of bladder tumors. Fifty-six patients who were given no preventive treatment against recurrences were taken as the control group. The patients in this series presented at the Okayama University Hospital between 1961 and 1976 and only the first recurrence after the primary operation was taken into consideration. There was no significant difference in the recurrence rates of the control and instillation groups
