Understanding the pathways driving the pathologic processes associated with obesity-induced non-alcoholic fatty liver disease (NAFLD) is critical to the identification of therapeutic targets. Although multiple animal models of NAFLD exist, high-fat-diet (HFD) administration has been a widely used model. A limitation of this model is that administration of a HFD to mice does not appear to induce significant NAFLD despite reproducibly inciting obesity, the metabolic syndrome, and hepatic steatosis. A potential explanation for this phenomenon is that the duration of HFD feedings is not long enough to produce significant non-alcoholic steatohepatitis (NASH). Thus, we employed a prolonged HFD feeding regime to examine the pathological processes associated with obesity-induced NAFLD. Male C57BL/6 mice were used given their susceptibility to diet-induced obesity. Mice were assigned to one of two diets for 20 months: Low Fat Diet (LFD, n=15) (14% Fat, 54% carbohydrate, 32% protein) or High Fat Diet (HFD, n=18) (60% Fat, 20% carbohydrate, 20% protein). Diets were administered to the mice for a period of 20 months. Our analysis focused largely on morphometric measures, metabolic markers, liver pathology, fibrosis, inflammation, and gut microbial profile. As expected, 20 months of HFD feedings augmented body weight compared to LFD-fed mice (p<0.05). This increase in body weight was in part due to the significant expansion of epididymal, retroperitoneal, and mesentery fat (p<0.05). In addition, HFD mice showed marked hepatosplenomegaly, a common indicator of chronic liver disease. HFD mice experienced significantly elevated concentrations of fasting glucose and insulin (p<0.05). These results were consistent with the HOMA index in which HFD mice exhibited insulin resistance (p<0.05). HFD-fed mice had severe steatosis; ballooning degeneration, lobular and portal inflammation, and pericellular fibrosis were evident. Oil red O staining exhibited macrovesicular accumulation of triglycerides in the hepatocytes of HFD mice. With regards to the microbiome, the HFD group showed a different microbial community structure compared to the LFD group; HFD-fed mice showed lower richness but higher evenness compared to the LFD-fed mice. At the phylum level, the HFD group had higher relative abundance of Firmicutes and lower abundance of Bacteroidetes compared to the LFD group. Our data indicates that chronic HFD consumption results in significant NAFLD that is related to changes in the gut microbiome profile; we report a significant increase in liver steatosis, ballooning degeneration and inflammation in association with an altered gut microbiome profile following prolonged HFD feedings in mice.