Background: Positive surgical margin (PSM) found following radical prostatectomy (RP) is known to affect subsequent recurrence and survival. The extent of PSM has been shown to impact clinical outcomes. We examined the effect of length of PSM, extent of disease at PSM and maximum Gleason score at PSM on oncologic outcomes. Methods: A retrospective review of 3971 patients undergoing RP for prostate cancer at our institution between1978-2009 revealed 1053 patients with PSM, out of whom 814 received no hormone therapy. The initial 175 patients were selected to maximize available follow-up, and their slides were re-reviewed for following parameters: length of PSM (mm), maximum Gleason score at PSM, and maximal extension of PSM (intraprostatic incision vs. extracapsular extension). Data was available in 107 patients who are the subject of this study. Multivariable Cox regression models were used to evaluate the impact of above features as well as age, preoperative PSA, pathologic Gleason score, stage and adjuvant radiotherapy on biochemical and clinical recurrence-free survival (RFS), and overall survival (OS). Results: Median follow-up was 17.6 years. Maximum extension of PSM was limited to intraprostatic incision in 63 (58.9%) and extracapsular in 44(41.1%) patients. Median length of PSM was 4 mm (range 1-55 mm); 41 (38.3%) with <3mm and 66 (61.7%) with >4mm. Maximum Gleason score at PSM was <6 in 70 (66.0%) and >7 in 36 (34%) patients. 10-yr PSA RFS, clinical RFS, and OS were 60.2%, 80.7%, and 60.2%, respectively. Multivariable Cox regression modeling showed the length of PSM >4mm and extracapsular extension as independent predictors of PSA RFS and clinical RFS. Age and extracapsular extension were independent predictors of OS. Conclusions: PSM >4mm and extracapsular extension have a higher risk of PSA and clinical recurrence after RP. These findings can help decision-making regarding adjuvant therapy in patients with PSM and should be reported by pathologists in addition to the presence of PSM.