Atotal of 2,574 residents in Yaeyama District of Okinawa, Japan, were investigated using real time ultrasonographyto determine the real prevalence of fatty liver in the general population and to define its associatedfactors. Overall prevalence of fatty liver was 14.0%. Prevalence of fatty liver in persons under 19 years old was only 1.2%, and increased with age to a maximumin persons 40-49 years of age and then decreased. For persons over 20 years old, obesity index and serum levels of triglyceride and total cholesterol were measured, and alcohol consumption was asked. Prevalence of fatty liver was significantly higher in drinkers than non-drinkers (p< 0.01), and increased with alcohol consumption. Furthermore, in persons not suffering from obesity prevalence of fatty liver was significantly higher in drinkers than in non-drinkers (p< 0.001). The results of logistic regression analysis indicated that obesity and elevated serum triglyceride level in both sexes, and alcohol in males weresignificant predictors of fatty liver. In conclusion, prevalence of fatty liver increased with age to a maximumin persons 40-49 years of age and overall was 14.0%. Obesity wasthe strongest associated factor in both sexes and in males alcohol wasalso a strong factor.