Background. The goal of this paper was to examine neighborhood deprivation and prostate cancer severity. Methods. We studied African American and Caucasian prostate cancer cases from the Pennsylvania State Cancer Registry. Census tract-level variables and deprivation scores were examined in relation to diagnosis stage, grade, and tumor aggressiveness. Results. We observed associations of low SES with high Gleason score among African Americans residing in neighborhoods with low educational attainment (OR = 1.34, 95% CI = 1.13-1.60), high poverty (OR = 1.39, 95% CI = 1.15-1.67), low car ownership (OR = 1.46, 95% CI = 1.20-1.78), and higher percentage of residents on public assistance (OR = 1.32, 95% = 1.08-1.62). The highest quartile of neighborhood deprivation was also associated with high Gleason score. For both Caucasians and African Americans, the highest quartile of neighborhood deprivation was associated with high Gleason score at diagnosis (OR = 1.34, 95% CI = 1.19-1.52; OR = 1.71, 95% CI = 1.21-2.40, resp.). Conclusion. Using a neighborhood deprivation index, we observed associations between high-grade prostate cancer and neighborhood deprivation in Caucasians and African-Americans.