The retrospective homogeneous study of 247 patients with follow-up from 12 months to 384 months (mean 88 months) and managed with or without intra-vesical instillations of thiotepa as prophylactic chemotherapy after surgical conservative treatment is compared with some literature's data principally multicentric randomized series. Statistics contradictions remain with no significative results for possible progression towards infiltration, better "free interval" between recurrences, and better recurrence rate for 100 patients/months. In this series the number of tumors recurrences in each bladder was evaluated: this mean rate of tumors recurrences/year is 1,7 without prophylactic thiotepa and only but always 1,08 with thiotepa. Prophylactic instillations chemoprophylaxy seems to be justified but must be emphasized: mitomycin C, BCG therapy would be better in the future?