Non-alcoholic fatty liver disease (NAFLD) has recently been recognized as a leading cause of abnormal liver function tests. Its spectrum ranges from simple steatosis, which is usually a benign and non progressive condition, to non-alcoholic steatohepatitis (NASH), which may progress to cirrhosis and hepatocellular carcinoma. NASH is thought to be almost 10% of NALFD and part of metabolic syndrome. NASH patients usually have insulin resistance, frequently combined with hypertension, hyperlipidemia and diabetes. The etiology of NASH remains unclear, but most investigators agree that the development of NASH requires underlying steatosis followed by a "second hit" that induces inflammation, fibrosis, or necrosis. The interaction of adipocytokines (TNF-alpha, adiponectin) with oxidative stress and lipid peroxidation has been postulated to play a key role in NASH. The basic therapy for NASH is an improved of lifestyle, including exercise and diet. Drug therapy should be considered as additional therapy.