OBJECTIVE: To assess the incidence of bladder carcinoma infiltrating the prostate and prostate adenocarcinoma in patients undergoing radical cystoprostatectomy due to bladder cancer, as well as to assess if the characteristics of the bladder neoplasia influence the prostatic involvement by this neoplasia. MATERIALS AND METHODS: We retrospectively assessed 60 male patients, who underwent radical cystoprostatectomy between July 1997 and December 2003. Mean age was 66.7 years (40 and 93 years). The product of radical cystoprostatectomies was checked for involvement of urethra and prostate parenchyma by the primary neoplasia, and for the presence of associated prostate adenocarcinoma. Bladder neoplasia characteristics, such as localization, size, multifocality, association with in situ carcinoma and histological grade, were studied in order to assess the possibility of using such characteristics as predictive factors of prostate infiltration by bladder urothelial carcinoma. RESULTS: We observed the presence of 20% of patients with bladder carcinoma infiltrating the prostatic urethra, 23.3% of patients with infiltration of the prostate parenchyma and 28.3% of patients with associate prostate adenocarcinoma, resulting in a total of 55% of patients with prostatic involvement (infiltrative bladder carcinoma and/or adenocarcinoma). We also observed a statistically significant correlation between tumor location in the trigone, the presence of in situ carcinoma and the histological grade of the bladder tumor with prostatic infiltration by the vesical neoplasia. CONCLUSION: The coexistence of prostatic neoplasia in patients operated for bladder neoplasia was frequent in our sample (55%). We observed that the prostatic infiltration by bladder tumors occurs more frequently with tumors located in the trigone, with associated in situ carcinoma and with high histological grade. There was no correlation between neoplastic infiltration of prostate and multifocality or size of the bladder tumor in the studied sample.