Thirty-two patients with superficial urinary bladder tumors were stratified for four variables and randomized after complete transurethral resection and/or fulguration of tumor to receive standard therapy with or without intravenous Poly I:C. Cystoscopies were performed at three- to four-month intervals for up to 48 months. While there was no statistically significant difference in the tumor recurrence rates in the two groups during the first year, a significant increase (P = 0.003) in survival at four years was observed between the Poly I:C group and the control group. The difficulties in evaluating the efficacy of anti-neoplastic agents in the treatment of superficial bladder tumors are discussed.