To evaluate the risk of tumor recurrence, we have studied the prognostic significance of the clinical features and chemoprophylaxis following transurethral resection (TUR) in 155 patients with primary superficial bladder carcinoma (Ta, T1, Tis). Thiotepa, adriamycin and cisplatin instillations in the bladder were utilized. The mean follow-up was 44 months (range 6-106). Considering the first tumor recurrence as an indication of failure of chemoprophylactic therapy, thiotepa was shown to afford better control. The significance of each variable (age, sex, drug, tumor stage, grade, number and size) was determined for each individual patient relative to the risk of recurrence after TUR and prophylactic treatment and the significant variables were then subjected to multivariant analyses (multiple logistic linear regression). Tumor number, stage and the drug utilized were shown to be significant prognostic factors (p = 0.04, 0.04 and 0.008, respectively). Based on the results of the multivariant analyses, mathematical models of prediction were assigned combining the more favourable individual prognostic values. The use of the mathematical models obtained to calculate the recurrence risk for each individual patient allowed us to classify these cases as being at high, medium or low risk for tumor recurrence.