PURPOSE OF REVIEW: To investigate the association between obesity and prostate cancer (PCa). RECENT FINDINGS: Obesity has been proposed to be involved in the pathogenesis of PCa through different biological mechanisms that include deregulation of the insulin axis, sex hormone secretion, adipokines signaling, and oxidative stress. Hypertrophic peritumoral adipocytes may also facilitate the local spread of PCa through the chemo-attraction of tumor cells. Clinical studies demonstrate that obesity might have clinical implications also in disease detection and management. Obese men have been shown to be less likely to be diagnosed with early-stage disease. Moreover, they are at increased risk of experiencing upgrading and upstaging when managed with active surveillance. However, the association between obesity and the risk of PCa recurrence and mortality after radical treatment is still debated. SUMMARY: Obesity may facilitate the development and progression of PCa trough different biologic mechanisms that may pose obese men at higher risk of advanced and high-grade disease. However, the association between obesity and long-term oncologic outcome after radical treatments appears unclear. Copyright © 2017 Wolters Kluwer Health, Inc. All rights reserved.