AIM: This study aimed to determine whether metabolic syndrome is directly or indirectly, through fatty liver, associated with elevated gamma-glutamyl transpeptidase (GGT) levels in Japanese women.METHODS: From 4 366 women who received their annual health check-up, 4 211 women were selected for analysis.All 4 211 women were negative for both hepatitis B surface antigen and antibody to hepatitis C virus. Clinical and biochemical variables were examined by using univariate and multivariate analysis.RESULTS: A raised GGT level (＞68 IU/L) was seen in 258 (6.1%) of the 4 211 women. In univariate analysis, all variables examined (age, body mass index, blood pressure,hemoglobin concentration, fasting blood glucose,glycosylated hemoglobin A1c, cholesterol, triglyceride, and uric acid) were associated with the elevated GGT level,whereas in multivariate analysis, four variables (age ≥ 50 yr,hemoglobin ≥14 g/dL, triglyceride ≥ 150 mg/dL, and presence of diabetes) were significantly and independently associated with raised GGT level. Clinical variables predicting the presence of ultrasonographic evidence of fatty liver were also examined by multivariate analysis; four variables were associated with the presence of fatty liver: BMI ≥ 25 kg/m2,hemoglobin ≥ 14 g/dL, triglyceride≥150 mg/dL, and uric acid≥ 7 mg/dL. There was no significant association between the raised GGT level and the presence of fatty liver.Hypertriglyceridemia was significantly and independently associated with both the raised GGT level and the presence of fatty liver.CONCLUSION: Metabolic syndrome seemed to be directly,not indirectly through fatty liver, associated with the raised GGT level in Japanese women.