Adiponectin, secreted specifically from adipocytes, is thought to play a key role in the metabolic syndrome. Plasma adiponectin concentrations were studied in 36 typical nonalcoholic fatty liver (NAFL) women which is commonly associated with the metabolic syndrome. They were diagnosed as NAFL by ultrasound brightness, slightly elevated serum ALT levels and the exclusion of history of alcohol abuse and other known liver diseases. Compared with 64 control women, NAFL had a significant increase in the variables of the metabolic syndrome, other hepatic enzymes and leptin levels, while a reduction in AST/ALT ratio and adiponectin before (mean ± SE: 7.2 ± 0.5 vs 9.0 ± 0.4 μg/ml, p<0.005) and after adjustment for body fat mass (0.24 ± 0.02 vs 0.34 ± 0.02, p<0.0001), atherogenic Index [(total cholesterol – HDLC)/HDLC: 3.2 ± 0.3 vs 4.6 ± 0.3, p<0.005] or calculated insulin resistance (HOMA-R) (6.6 ± 1.9 vs 8.6 ± 0.9, p<0.005). BMI and amylase were positive, and adiponectin/BMI was negative significant independent determinants of ALT value in multiple regression model. In conclusion, while hypoadiponectinemia was observed in NAFL, hypoadiponectinemia provides the possibility of fat accumulation in the liver.