Background: Inflammatory bowel disease (IBD) has long been considered a risk factor for increased bowel toxicity from radiation therapy (RT); however, minimal evidence exists for patients with prostate cancer (PC) and IBD. Methods: The tumor registry was queried for patients with both IBD and PC from 2000-2010. A chart review was conducted for patients who received RT for PC. All patients carried the diagnosis IBD as defined by either Crohn’s disease or ulcerative colitis. RT specifics and radiation toxicity (acute and late) data were collected. Results: Eighteen patients met the inclusion criteria for PC and IBD diagnoses with radiation therapy treatment. Twelve were treated with external beam radiation therapy (EBRT), and 6 were treated with low dose rate (LDR) brachytherapy. Average length of follow-up was 12 years (median 9.54, range 0.42-19.9). Most patients had well controlled baseline bowel function on medical management. Twenty-two percent were in remission from IBD without any form of treatment; 56% were actively taking 5-ASA; 17% were prescribed prednisone; and 6% were taking Remicade. Sixty percent of patients (9/15) reported grade 0 (G0) diarrhea at baseline prior to radiation therapy. Forty percent (6/15) suffered grade 1 (G1) diarrhea at baseline. No baseline proctitis existed. Two patients reported ostomy prior to radiation. Following radiation treatment, 78% (14/18) of patients experienced G0 diarrhea while 22% (4/18) reported G1 diarrhea. No patients suffered from greater than G1 diarrhea. Sixty-seven percent (12/18), 17% (3/18) and 17% (3/18) of patients experienced G0, G1, and G2 proctitis, respectively. No patients suffered post-radiation stricture formation. All patients with G2 proctitis following RT received 3dCRT. Conclusions: No available published data explores RT for patients with PC and IBD. This retrospective review offers valuable insight into appropriate counseling for a rare patient subset. EBRT was associated with improvement in late G1 diarrhea rates. Grade 2 proctitis was only encountered among 3dCRT patients. No post-radiation stricture or ostomy placements occurred. Our findings suggest that IBD patients experience minimal toxicity with IMRT-based radiation therapy.