OBJECTIVES: Recent advances in prostate cancer radiation therapy (RT) technology have led to the development of costlier treatments such as intensity-modulated radiation therapy (IMRT) compared to the prior standard, conventional radiation therapy (CRT). This study examines the two treatment modalities to determine if racial disparities in morbidity and disease control may be explained by differential use of IMRT versus CRT. METHODS: A population-based study was conducted using Surveillance, Epidemiology, and End Results (SEER)-Medicare linked data from 2000 through 2009 for patients with non-metastatic prostate cancer. Adjusted Cox Proportional Hazards models were conducted, adjusting for demographic and clinical characteristics. Results are presented as (Adjusted Hazard Ratio [95% Confidence Interval]). In subjects without prior morbidity at RT, the rate of recurrence, hip fracture, erectile dysfunction, disorders related to gastrointestinal, and urinary (incontinence and non-incontinence) morbidity were compared by race with IMRT as the referent group.   RESULTS: Approximately 10,976 men [524 African-American (AA) CRT; 423 AA IMRT; 4,746 Caucasian CRT; 5,283 Caucasian IMRT] met study eligibility. Diffusion of IMRT was slower among AA compared to Caucasians (p<0.001). Caucasians receiving CRT were at a greater risk for hip fracture [1.29; (1.16, 1.43)], cancer recurrence [1.13; (1.04, 1.23)], or urinary incontinence [1.09; (1.01, 1.19)] than those receiving IMRT. No estimates comparing AA CRT recipients to AA IMRT recipients reached statistical significance, though cancer recurrence, erectile dysfunction, and gastrointestinal morbidity rates were greater for CRT subjects  CONCLUSIONS: There were no statistically significant racial disparities in morbidity and disease control related to differential use of IMRT versus CRT. However, diffusion of IMRT was significantly slower among AA. Future research should include more years of follow-up data and a larger sample of AA in order to understand whether measured differences in treatment diffusion achieve clinical significance sufficient to explain a portion of the racial disparity in prostate cancer mortality.