The aim of this study was to investigate blood coagulation times in genetically obese rats and diet-induced obese (DIO) mice in order to clarify the relationship between visceral obesity and blood coagulation. WBN/Kob-Lepr(fa) (fa/fa) rats, a genetically obese model, exhibited a significantly shorter activated partial thromboplastin time (aPTT) and prothrombin time (PT) than age-matched Wistar rats. C57BL/6J mice fed a high-fat diet (60%), a DIO model, exhibited significantly shorter aPTT, PT and thrombin time than lean mice fed a standard diet. Higher body weight, visceral fat weight and insulin resistance were also shared by fa/fa rats and DIO mice. These results suggest that visceral obesity is related to accelerated blood coagulation in addition to disrupted metabolism of glucose and lipids.