To prevent postoperative recurrence a randomized prospective trial was performed on 45 patients with bladder cancers by dividing them into 2 groups given either UFT therapy alone or UFT therapy in combination with Bestatin. In principle, oral administration of these drugs was initiated 4 weeks postoperatively and continued for a period of 1 year. Bestatin was given at the dose of 30 mg/day after breakfast per os, and UFT at the dose of 400 mg/day twice a day per os. After a median follow-up period of 628 days the relapse-free rate was 43.5% for the group given UFT alone and 81.8% for the group given a combination of UFT plus Bestatin, showing a significantly more favorable result in the latter group. In patients with a solitary and papillary tumor the relapse-free rate was significantly better in the UFT plus Bestatin group compared with the group of UFT alone. Accordingly, it was suggested that postoperative administration of UFT in combination with Bestatin is more effective in preventing recurrence of bladder cancer, compared with the administration of UFT alone.