OBJECTIVES:The aims of this study were to test the possible association between nonalcoholic fatty liver disease (NAFLD) and iron and insulin resistance, and to determine the prevalence of NAFLD in apparently healthy obese subjects. DESIGN: Cross-sectional, clinical epidemiologic study. SUBJECTS: A total of 210 apparently healthy obese patients, aged from 18 to 65 y, with a body mass index (BMI) of 28 kg/m 2 or more, were enrolled in a body weight reduction program in our hospital. MEASUREMENTS: All the subjects underwent screening and preprogram examinations, including anthropometric data measurements, biochemistry testing, and ultrasonography of the liver. NAFLD was defined as fatty liver diagnosed by ultrasonograpgy plus persistent elevation of alanine aminotransferase (ALT) levels. RESULTS: Of the 210 patients, 80% (168/210) had fatty liver. Persistent ALT elevation in two separate tests was further detected in 25.6% (43/168) of patients. Multiple logistic regression analysis showed waist circumference and insulin resistance to be independently associated with fatty liver. Serum ferritin level and insulin resistance were two major risk factors predicting NAFLD. CONCLUSION: The prevalence of NAFLD was 20.5% (43/210) in obese patients. As both hyperinsulinemia induced by insulin resistance and iron overload represented by ferritin elevation might damage hepatocytes, we concluded that these two factors were significantly associated with NAFLD in obese patients.