Background: To compare 10 year treatment complication outcomes of radical prostatectomy(RP) vs external beam radiation therapy(EBRT) vs brachytherapy(BT) for patients with intermediate risk prostate cancer(IRPC). Methods: A retrospective analysis was performed on 1,503 IRPC patients who underwent treatment from 2004 to 2007, using univariate comparisons. 819 underwent RP, 574 underwent EBRT, and 110 underwent BT using iodine-125. Urinary and rectal complications for RP were graded as severe if patients required ≥ 3 pads/diapers per day, required chronic use of condom catheter or penile clamp, daily self-catheterization, placement of sling or artificial urinary sphincter, or developed rectal fistula/incontinence. Complications for EBRT and BT were graded as severe if they were classified as grade 3 or 4 on the Radiation Therapy Oncology Group grading system for late effects. For erectile dysfunction, the prevalence of patients requiring injections, pumps or penile implants were calculated after a minimum of 1 year of follow up. Results: Median follow up was 10.0 years for RP, 9.6 for EBRT, and 9.8 for BT. Neoadjuvant androgen deprivation therapy was given in 0.6% for RP patients vs 58.9% of EBRT vs 12.7% of BT, p < 0.0001. Median age for RP vs EBRT vs BT was 62.1, 70.8, 65.3, p < 0.0001. The 10-year prevalence of severe urinary complications for RP vs EBRT vs BT was 10.1%, 12.5%, 4.6%, p = 0.04. The percentage of patients having a pre-treatment American Urological Association(AUA) urinary score for RP vs EBRT vs BT was 7.3%, 11.5%, 97.3%, p < 0.0001. The 10-year prevalence of severe rectal complications for RP vs EBRT vs BT was 0.5%, 1.6%, 0.0%, p = 0.06. The 10-year prevalence of erectile dysfunction devices for RP vs EBRT vs BT was 24.3%, 6.6%, 8.2%, p < 0.0001. Conclusions: After 10 years of follow-up, BT had the lowest rate of severe urinary complications, which may due to using the AUA score to avoid implanting those who had significant baseline obstructive voiding symptoms. EBRT had a higher rate of severe rectal complications. RP had the highest probability of undergoing treatment using erectile dysfunction devices, despite having younger patients.