OBJECTIVE: Erectile dysfunction (ED) is considered an early manifestation of cardiovascular disease (CVD), endothelial dysfunction being the link between CVD and vasculogenic ED. Mitochondrial reactive oxygen species (mtROS) have been involved in the vascular complications of metabolic disorders. The aim of this study was to assess the impact of obesity on endothelial function, redox metabolism and mitochondrial bioenergetics of penile erectile tissue. METHODS: Wistar rats were fed a high-fat diet (HFD) or standard diet (STD), and penile vascular function was assessed in microvascular myographs. mtROS levels were measured by mitoSOX (O RESULTS: Endothelium-dependent relaxations to acetylcholine (ACh) and to the mitoK CONCLUSIONS: Mitochondrial dysfunction with impaired bioenergetics and reduced mitoK