Non- alcohol fatty liver disease (NAFLD) is the commest liver disease worldwide. In Western countries, prevalence between 20 and 30 % is reported among the adult population. Nutrition, excess eating food rich in saturated fats and high caloric food, along with decrease in eating vegetables, fruits, proteins, and 3-Fatty Acids are main contributors of NAFLD growth. Human beings have nearly one thousand bacterial organisms and several millions of bacteria, with 150-time more genes than the human genome colonizing in the human gasterointestinal tract. Lactobacillus, Peptoniphilus, Ruminococcus, Clostridium, and Eubacteria), Bacteroides, and Prevotella are the two main phyla in the human intestines. However, the components and presence of gut microbiota varies due to a high heterogeneity among people due to several factors as age, sex, general conditions, pregnancy, hormonal changes, travelling, infection, and drugs as chemotherapeutic agents or proton pump inhibitors. Our aim is to demonstrate the effect of gut microbiota in development of NAFLD.