AIM: To evaluate the association between the severity of liver steatosis and metabolic syndrome in apparently healthy Korean adults. METHODS: We examined 1 022 men and women, aged 30-79 years, who participated in a health screening test. A standard interview, anthropometrics, biochemical studies, and abdominal ultrasonography were conducted for each participant. Metabolic syndrome was defined according to the National Cholesterol Education Program Adult Treatment Panel Ⅲ, with a modification for the waist circumference cut-off level. The severity of liver steatosis was evaluated using liver ultrasonography, and serum aspartate aminotransferase (AST), alanine aminotransferase (ALT), and γ-glutamyl transferase (γ-GT) levels were determined. RESULTS: Ultrasonographic liver steatosis was strongly associated with metabolic syndrome and common metabolic abnormalities. Compared with people without steatosis, people with mild, moderate, and severe steatosis had adjusted odds ratios for metabolic syndrome of 1.72 (95%CI, 1.01-2.94), 2.89 (1.75-4.76) and 3.53 (1.25-9.98) in men, and 2.86 (1.64-5.01), 3.19 (1.80-5.65) and 3.70 (0.82-16.73) in women, respectively. The serum AST level was not associated with metabolic syndrome. The serum ALT and γ-GT levels were significantly associated with metabolic syndrome in men but not in women. CONCLUSION: The occurrence of metabolic syndrome shows a stronger association with the severity of ultrasonographic steatosis than with the serum liver enzyme levels. The degree of fatty infiltration detected on ultrasonography can be used as an indicator of liver dysfunction attributable to metabolic abnormalities. METHODS: We examined 1 022 men and women, aged 30-79 years, who participated in a health screening test. A standard interview, anthropometrics , biochemical studies, and abdominal ultrasonography were conducted for each participant. Metabolic syndrome was defined according to the National Cholesterol Education Program Adult Treatment Panel III, with a modification for the waist circumference cut-off level. The severity of liver steatosis was evaluated using liver Ultrasonography, and serum aspartate aminotransferase (AST), alanine aminotransferase (ALT), and γ-glutamyl transferase (γ-GT) levels were determined. RESULTS: Ultrasonographic liver steatosis was strongly associated with metabolic syndrome and common metabolic abnormalities. steatosis, people with mild, moderate, and severe steatosis had adjusted odds ratios for met abolic syndrome of 1.72 (95% CI 1.01-2.94), 2.89 (1.75-4.76) and 3.53 (1.25-9.98) in men and 2.86 (1.64-5.01), 3.19 (1.80-5.65) and 3.70 (0.82-16.73 The serum AST level was not associated with metabolic syndrome. The serum ALT and γ-GT levels were significantly associated with metabolic syndrome in men but not in women. CONCLUSION: The occurrence of metabolic syndrome shows a stronger association with the severity of ultrasonographic steatosis than with the serum liver enzyme levels. The degree of fatty infiltration detected on ultrasonography can be used as an indicator of liver dysfunction attributable to metabolic abnormalities.