Vitis thunbergii (VTE), an indigenous wild grape of Taiwan, has been widely used as folk medicine in Taiwan. In this study, we investigated the anti-obesity effect and safety of VTE in high-fat diet-fed C57BL/6JNarl mice.Male C57BL/6JNarl mice were randomly divided into three groups fed with diets for 7 weeks: a high-fat diet (control group), high-fat diet with 0.375% V. thunbergii extract (1× VTE group), and high-fat diet with 0.75% V. thunbergii extract (2× VTE group). Body weight and food intake were recorded. The resected epididymal fat, liver, and kidney were collected for further analysis.Our data suggested an anti-obesity effect of VTE in high-fat diet-fed C57BL/6JNarl mice, as evidenced by the decreased body weight gain, epididymal fat pads weight, adipocyte size, liver weight, and hepatic fat deposition. Moreover, VTE supplementation lowered the level of blood glucose and serum triglyceride. However, histological changes and parallel elevation of serum GOT and GPT level demonstrated a potential hepatotoxicity in 0.75% VTE-supplemented group. The augmented liver injury was accompanied by fibrotic change, possibly through activation of α-SMA-positive matrix-producing cells.The findings suggest that VTE supplementation showed anti-obesity effect and preferentially ameliorated glucose and lipid dysregulation in C57BL/6JNarl mice fed with a high-fat diet. However, the long-term use of VTE should be cautioned because of a potential hepatotoxicity, especially at higher doses.