It was retrospectively analyzed whether intravesical instillation of bacillus Calmette-Guerin (BCG) or anti-cancer agents had prophylactic effect or not after removal of superficial bladder tumors. The results over a follow-up period ranging from 6 to 40 months showed 23.8 per cent recurrence in group 1 patients treated with BCG (21 patients), 46.7 per cent recurrence in group 2 treated with anti-cancer agents (45 patients) and 52.3 per cent recurrence in the group 3 (127 patients) which were not received any intravesical drugs. Long-term results among the 3 groups calculated with Kaplan-Meier method demonstrated that the instillation of BCG or of anti-cancer agents was more useful for prophylaxis, compared with the actuarial non-recurrence rates of group 3. The instillation of BCG showed good prophylactic effects especially in recurrent, grade 2 and pTa bladder tumors. The instillation of anti-cancer agents showed to provide prolonged protection from recurrence, but the instillation of BCG did not.