Objective: 10-30% of patients with T(1)/T(2) prostate cancer submitted to radical prostatectomy ultimately fail. It may be important to detect failure as early as possible in order to evaluate the extent of recurrent/residual disease and initiate adjuvant therapy. Subjects and Methods: 100 consecutive patients with localized prostate cancer treated by radical prostatectomy have been monitored using the hypersensitive Pros-check prostate-specific antigen (PSA) assay (detection level 0.1 ng/ml). The predictive value of positive surgical margins, involvement of seminal vesicles and perineural spaces as well as Gleason’s score for biological failure(persistent or recurrent detectable PSA) has been retrospectively evaluated. Results: Overall 40% of the patients had biological failure (defined as persistence of a detectable or rising PSA after undetectability) and 38% had positive surgical margins. The three main predictive criteria of biological failure were capsular perforation, involvement of seminal vesicles and/or positive margins. All patients in whom these criteria were positive progressed. Seminal vesicle invasion was associated with biological failure in 95% of the cases. 66.7% of the patients with extracapsular disease but no seminal vesicle invasion progressed. 15% of pT(2) patients experienced a persistent/recurrent postoperative PSA and were upstaged to pT(3) after réévaluation of the specimen. Conclusion: Efforts should be made to increase the preoperative evaluation of seminal vesicle and pericapsular status by a more sophisticated technique of prostate biopsy in order to avoid noncurative surgery.