The independent prognostic importance of microscopic bladder neck involvement by prostate cancer in radical prostatectomy is questionable. We studied a cohort of 1845 patients to determine the significance of microscopic bladder neck involvement. Bladder neck involvement was defined as prostate cancer present within the coned bladder neck. We further categorized the cases as 'true bladder neck involvement' and 'false bladder neck involvement.' True bladder neck involvement required prostate cancer within thick smooth muscle bundles without intermixed benign prostatic glands. False bladder neck involvement was characterized by prostate cancer intermixed with benign prostatic glands. Bladder neck involvement was analyzed in relation to preoperative serum prostate-specific antigen (PSA) level, extraprostatic extension, seminal vesicle involvement, positive surgical margin, lymph node involvement, radical prostatectomy Gleason score, and tumor volume. Of the 90 patients (4.9%) with microscopic bladder neck involvement, 63 were further classified as true bladder neck involvement and 27 as false bladder neck involvement. In univariate model, both types of bladder neck involvement (P<0.001), true (P<0.001), and false (P<0.040), were significantly associated with increased PSA-recurrence risk compared to bladder neck negative cases. In multivariate model the PSA-recurrence relative risk associated with bladder neck involvement (true or false) was not a significant independent prognostic factor. Extraprostatic extension, seminal vesicle involvement, positive surgical margin, lymph node involvement, PSA, and Gleason score were significant independent predictors of PSA recurrence. The time to biochemical recurrence in patients with bladder neck involvement was similar to that of pT2 with positive surgical margin or pT3a with negative surgical margin patients (Kaplan-Meier curves). Bladder neck involvement was associated with other adverse pathologic features, but was not an independent predictor of PSA recurrence. In view of the previous and current data, the staging system for bladder neck involvement should be revised and patients may be best categorized as having pT3a disease. © 2009 USCAP, Inc All rights reserved.