Purpose We evaluated whether preoperative erectile function is associated with pathologic features in the patients who underwent radical prostatectomy (RP). Materials and Methods We reviewed medical records of 1,743 men who underwent RP from November 2003 through May 2012. Of these, 50 patients who had prior hormone therapy and 272 patients who had lacking data of International Index of Erectile Function-5 (IIEF-5) were excluded. Men whose IIEF-5 was in the lower 25 percentile were assigned as Low Erectile Function group and the others were assigned as Control group. We compared pathologic features using univariable and multivariable logistic regression analysis between two groups. Results A total of 1,421 patients were included in the analysis. Patients’ age was 65.8 ± 6.7 years and prostate-specific antigen (PSA) was 12.8±16.1 ng/mL. Median and low 25 percentile of IIEF-5 were 14 and 8, respectively. Low Erectile Function group (IIEF-5<8) had higher risk to have high Gleason score (≥7(4+3), odds ratio (OR) 1.642, p<0.001) and large tumor volume (≥5 mL, OR 1.292, p=0.042). Even after adjusting age, year of surgery, body mass index, Charlson comorbidity index, PSA, clinical stage and biopsy Gleason score, Low Erectile Function group still had higher risk of high Gleason score (OR 1.910, p<0.001) and large tumor volume (OR 1.390, p=0.04) by multivariable logistic regressions. Conclusions Lower erectile function before RP was associated with higher Gleason’s score and larger tumor volume in final pathology. Thus, erectile function could be a surrogate barometer for prostate cancer aggressiveness.