There is limited data regarding the association between the expression of cell cycle-regulating molecules and the response of patients with urothelial carcinoma in situ (CIS) to bacillus Calmette-Guerin (BCG) therapy. To examine the relationship between p16, pRb and p53 expression in bladder CIS and patient response to initial BCG therapy, we performed immunohistochemical studies for 27 patients with bladder CIS. Overexpression of p16, pRb, and p53 was observed in 37%, 41%, and 48% of patients, respectively. Initial BCG therapy was effective in 21 patients (78%). Coexistence of papillary urothelial carcinoma, depth (pTa or pT1) and grade of coexisting papillary carcinoma did not affect the response to BCG therapy. pRb overexpression had a significant relationship to poor response to BCG therapy (P = 0.027). The results of this study indicate that overexpression of pRb in bladder CIS predicts poor response of intravesical BCG instillation and status of p16 and p53 may not be predictive of initial BCG failure.