 Results from two large population-based studies are extremely useful in defining the prevalence of NAFLD in the general US adult population.4,5 The Dallas Heart Study used liver imaging to assess the prevalence of fatty liver in over 2200 adults. The overall prevalence of fatty liver in that study was 31 with a range of 24-45 of the population demonstrating hepatic steatosis. Of note, most individuals with elevated liver fat content did not demonstrate aminotransferase elevations. The latter finding helps to explain why NHANES III, another large population-based study, suggested a much lower prevalence of NAFLD in the general US adult population. In NHANES III, serum aminotransferases were used to assess NAFLD prevalence in over 15,000 adults and that approach suggested that 5.5 of the population has NAFLD. Based on the results of the Dallas Heart Study it is likely that the approach used in NHANES III underestimated the true prevalence of NAFLD in US adults. In any case, the net results from these two studies suggest that between 5.5 to 31 of the adult US population has NAFLD. To appreciate the significance of this finding, it is useful to compare the prevalence of NAFLD to that of hepatitis C, which is thought to exist in 1.8 of the US population.6 NAFLD is three to ten times more common than hepatitis C-related liver disease in the US. 