Objectives : Non-alcoholic fatty liver disease (NAFLD) is known to be increasing and becoming a health-related issue worldwide. This study aimed to analyze its prevalence and characterize NAFLD. Methods : NAFLD-related papers were surveyed via PubMed and in Korean medical journals, and then the prevalence and pathology were reviewed. Results : The prevalence of NAFLD in the general population is around 10~30% worldwide. The prevalence of NAFLD in Korea is estimated as 15~30%, which is higher than in China and Japan. The most important etiological-factors of NAFLD include central obesity resulting from excessive calorie intake and less physical activity, which lead to adiponectin hypoactivity and insulin resistance. The Oriental medicine view point of NAFLD pathology is phlegm-dampness by dysfunction of free flow in liver. Conclusions : This study provided an overview of the prevalence and pathology of NAFLD, and can support the development of a strategy for traditional Korean medicine-based prevention or treatment of NAFLD.