Taken together, our results show that E1B-55 kD-deleted adenovirus replicates and hence lyses bladder cancer cells with mutant p53much more efficient than those with wild-type p53. Thus, E1B-deleted adenovirus may have therapeutic potential, especially in combination with adenoviral vector expressing K1–5, for the treatment of bladder cancer. The gene discussed is TP53; the disease is urinary bladder cancer.