Behavior of transitional cell carcinoma of the bladder during the third decade of life remains a controversial subject. During the period 1980-1988, we treated 7 patients (4 male and 3 female), 25 years of age or less (mean age 19.3, range 14-25), with transitional cell carcinoma of the bladder. Until now, all patients are alive and without disease during 12-50 months after surgery. In 6 of the 7 patients, endoscopic resection was the choice treatment for superficial stage A/O. The seventh patient underwent a partial cystectomy for a B1 Jewet stage cell carcinoma. We conclude that transitional cell carcinoma of the bladder in patients under 25 years of age has a less aggressive biological behavior. Therefore, ultrasonographic examinations and serial urine cytology represent the elective test for follow-up. Cystoscopy would only be performed in doubtful cases.