OBJECTIVES: To determine which patients may benefit from prostate-sparing surgery and which factors are predictive of invasive prostatic involvement. MATERIALS AND METHODS: A total of 717 men underwent radical cystoprostatectomy (RC) for bladder transitional cell carcinoma (TCC) between 1978 and 2002. Analysis of prostatic urethral involvement by transitional cell carcinoma (pTCC) and of invasive prostatic involvement by TCC was performed according to recurrence, presence of carcinoma in situ (CIS) and multifocality, previous intravesical chemotherapy, grade, stage and location of bladder tumor, presence of CIS in precystectomy transurethral resection (TUR) and indication for RC. RESULTS: pTCC was present in specimens from 140 patients (19.5%), of whom 83 (59.3%) showed invasive prostatic involvement. Tumor location at the trigone or bladder neck (p = 0.011, OR 2.29, 95% CI 1.21-4.33) and a history of CIS (p = 0.003, OR 2.03, 95% CI 1.27-3.22) were independent predictors of pTCC. Presence of a solitary T2-T3 bladder tumor was a predictive factor for invasive prostatic involvement (p = 0.001, OR 3.73, 95% CI 1.70-8.16). Neither solitary tumors nor T2-T3 bladder tumors showed significant differences in 5 year specific survival (p = 0.277 and p = 0.618 respectively) when comparing patients according to the presence of superficial or invasive prostatic involvement. Bladder tumor stage in precystectomy TUR was a predictor of disease-specific survival (p = 0.018, OR 1.62, 95% CI 1.08-2.44). CONCLUSIONS: Patients with a history of CIS and bladder tumor location at the trigone or bladder neck are not candidates for prostate-sparing surgery. The only variables that can predict invasive prostatic involvement are the presence of a solitary T2-T3 bladder tumor at the trigone or bladder neck.