Background The presence of positive surgical margins after radical prostatectomy is a well-established adverse prognostic factor. While some of these patients experience an aggressive clinical course, others do not. Making decisions about adjuvant or salvage treatment after positive surgical margins is particularly challenging. To better address this challenge, we present the results of a risk stratification model developed through detailed analysis of tumor characteristics at the surgical margin. Methods We retrospectively analyzed 63 patients with positive surgical margins after radical prostatectomy who had no lymph node involvement and had not received neoadjuvant or adjuvant therapy. The BEUN risk score integrates four pathologic features: number of positive foci, total margin extent, Gleason score at the margin, and concordance between margin and specimen grade. Based on the total score, patients were stratified into three risk categories: low risk (3-5 points), moderate risk (6-8 points), and high risk (9-12 points). Cox regression analysis identified predictors of biochemical recurrence-free survival (BRFS) and clinical progression-free survival (CPFS). Survival analyses across risk groups were performed using the Kaplan-Meier method. Results Biochemical recurrence occurred in 20 patients (32%) and clinical progression in 20 patients (32%). On multivariate analysis, the BEUN risk score independently predicted both BRFS (HR 1.23, 95% CI 1.08-1.40, p = 0.002) and CPFS (HR 1.28, 95% CI 1.06-1.54, p = 0.010). High-risk patients had a 4.7-fold higher hazard of biochemical recurrence (p = 0.001) and a 5.3-fold higher hazard of clinical progression (p = 0.011) compared with low-risk patients. Five-year BRFS rates were 58.8%, 24.1%, and 5.9% for low-, moderate-, and high-risk groups, respectively (p < 0.001). Conclusion The BEUN risk score is an independent predictor of BRFS and CPFS.This tool may provide additional support for postoperative risk stratification in patients with positive surgical margins.