Over the past couple of decades, nonalcoholic fatty liver disease (NAFLD) and nonalcoholic steatohepatitis (NASH) have become the number one cause of liver disease in Western countries. Recent data confirm that NAFLD and NASH play an equally important role in the Middle East, Far East, Africa, the Caribbean, and Latin America. The prevalence of NAFLD/NASH continues to increase along with its associated risk factors, including metabolic disorder, obesity, diabetes and hypertension. Therefore, understanding the mechanism of these diseases has become a priority. Recent investigations into the effect of chronic liver inflammation have shed light on the role of both the adaptive and innate immune systems in both NAFLD and NASH. Long suspected to play a part in such metabolic disorders along with nutrition and hormonal imbalances, the immune system has been of great interest to researchers for development of specific drug targets to maximize glucose regulation, minimize inflammatory damage to tissues and prevent the development of fibrosis that can lead to liver failure.