OBJECTIVE To create a rat insulin resistant fatty liver model. METHODS 14 male Wistar rats were randomly divided into a model and a control group. The model rats were fed a high-fat diet (45% of energy from fat) for 8 weeks, and the control group a standard diet (19% of energy from fat). Insulin sensitivity was measured with glucose infusion rate (GIR) by the euglycermic hyperinsulinemia clamp technique. The aminotransferase, triglyceride (TG), free fatty acid (FFA), superoxide dismutase (SOD) and malondialdehyde (MDA) were measured by biochemical methods, and insulin was measured by radioimmunoassay. The histological and ultrastructural changes of all rat livers were scored using light and electron microscopy. RESULTS Rats fed the high-fat diet developed panlobular macrovesicular steatosis, lobular inflammatory cell infiltration and abnormal mitochondria, whereas those fed the standard diet had normal livers. All model group rats had elevated levels of aminotransferase, TG, FFA, insulin and liver index, and low GIR. In addition, the high-fat diet increased MDA and decreased SOD. CONCLUSION A fatty liver and insulin resistance model was successfully developed in rats fed a high-fat diet for 8 weeks, which provided a useful experimental tool for elucidating pathogenesis and treatment of fatty liver.