During the 4 decades since the first introduction of intravesical chemotherapy, 3,899 patients were enrolled in 22 randomized prospective controlled studies. Of these 22 studies 13 reported a statistically significant benefit of intravesical chemotherapy. With varying followup, the reported decrease in the incidence of patients with tumor recurrence averaged only 14% (range -3 to +43%). Unfortunately, long-term (5-year) studies show no decrease in the incidence of recurrent tumor. Maintenance chemotherapy has failed to improve these results and data suggest that a single early postoperative instillation may, in fact, be most effective. Among 10 studies that include progression data none showed decreased tumor progression, and overall among 2,011 randomized patients progression occurred in 7.5% of those receiving intravesical chemotherapy and 6.9% of those treated by surgery alone. Since intravesical chemotherapy has been demonstrated in animal models to be carcinogenic, these data raise the concern that intravesical chemotherapy might possibly be carcinogenic in humans. In the absence of demonstrated long-term benefit we question the advisability of routine prophylactic intravesical chemotherapy.