Controversies exist about the most appropriate management for patients with incidental prostate cancer after surgery for benign prostatic hyperplasia (BPH).To test the accuracy of preoperative clinical variables in predicting the presence of residual disease and biochemical recurrence in patients with incidental prostate cancer treated with radical retropubic prostatectomy.We analyzed 126 T1a-T1b prostate cancers diagnosed at surgery for BPH between 1995 and 2007.All patients underwent radical retropubic prostatectomy within 6 mo of surgery for BPH.Univariate and multivariate logistic regression models addressed the association between the predictors (age, prostate-specific antigen [PSA] before and after surgery for BPH, T1a-T1b stage, prostate volume, and Gleason score at surgery for BPH) and the presence of residual cancer at radical retropubic prostatectomy. Cox proportional hazards regression analyses tested the relationship between the same predictors and the rate of biochemical recurrence after radical retropubic prostatectomy.Seventy-five (59.5%) patients were stage T1a and 51 (40.5%) were stage T1b. At radical retropubic prostatectomy, 21 (16.7%) patients were pT0 and seven (5.6%) patients had extraprostatic disease (pT3). PSA before and after surgery for BPH and Gleason score at surgery for BPH were the only independent predictors of residual cancer at radical retropubic prostatectomy (all p<0.04). Stage (T1a vs T1b) did not predict residual cancer or the rate of biochemical recurrence. With a mean follow-up of 57 mo, the 5- and 10-yr biochemical recurrence-free survival rates were 92% and 87%, respectively. PSA after surgery for BPH and Gleason score at surgery for BPH were the only significant multivariate predictors of biochemical recurrence (all p<0.04). The main limitation of this study is the requirement of an external validation before implementation of the clinical recommendations.PSA measured before and after surgery for BPH and Gleason score at surgery for BPH were the only significant predictors of the presence of residual cancer at radical retropubic prostatectomy. PSA measured after surgery for BPH and Gleason score at surgery for BPH were the only independent predictors of biochemical recurrence after radical retropubic prostatectomy.