BACKGROUND: We compared upgrading and upstaging rates in low risk and favorable intermediate risk prostate cancer (CaP) patients according to racial and/or ethnic group: Mexican-Americans and Caucasians. METHODS: Within Surveillance, Epidemiology and End Results database (2010-2015), we identified low risk and favorable intermediate risk CaP patients according to National Comprehensive Cancer Network guidelines. Descriptives and logistic regression models were used. Furthermore, a subgroup analysis was performed to test the association between Mexican-American vs. Caucasian racial and/or ethnic groups and upgrading either to Gleason-Grade Group (GGG II) or to GGG III, IV or V, in low risk or favorable intermediate risk CaP patients, respectively. RESULTS: We identified 673 (2.6%) Mexican-American and 24,959 (97.4%) Caucasian CaP patients. Of those, 14,789 were low risk (434 [2.9%] Mexican-Americans vs. 14,355 [97.1%] Caucasians) and 10,834 were favorable intermediate risk (239 [2.2%] Mexican-Americans vs. 10,604 [97.8%] Caucasians). In low risk CaP patients, Mexican-American vs. Caucasian racial and/or ethnic group did not result in either upgrading or upstaging differences. However, in favorable intermediate risk CaP patients, upgrading rate was higher in Mexican-Americans than in Caucasians (31.4 vs. 25.5%, OR 1.33, P = 0.044), but no difference was recorded for upstaging. When comparisons focused on upgrading to GGG III, IV or V, higher rate was recorded in Mexican-American relative to Caucasian favorable intermediate risk CaP patients (20.4 vs. 15.4%, OR 1.41, P = 0.034). CONCLUSION: Low risk Mexican-American CaP patients do not differ from low risk Caucasian CaP patients. However, favorable intermediate risk Mexican-American CaP patients exhibit higher rates of upgrading than their Caucasian counterparts. This information should be considered at treatment decision making.