in a population-based sample, after excluding alcohol consumption, hepatotoxic drugs and hepatitis band c infected, we investigated if alanine-aminotransferase (alt) was associated with metabolic syndrome and insulin resistance, and if this association was caused by non-alcoholic fatty liver disease (nafld). the sample (432 female and 119 male) was divided into two alt thresholds corresponding to the 50th and 75th percentiles (p) (female ≤ 15 and ≤ 19 u/l; male ≤ 17 and ≤ 23 u/l, respectively). blood pressure, body mass index, waist circumference, cholesterol, hdl cholesterol (hdlc), triglyceride (tg), tg/hdlc ratio, glycemia and homeostasis model assessment of insulin resistance (homa-ir) were compared between those above and below each alt threshold. female placed above the 50th p of alt had higher levels of tg/hdlc ratio (p=0.029), glycemia (p=0.028), and homeostasis model assessment of insulin resistance, (p=0.045), and above the 75th p had higher sbp (p=0.036), dbp (p=0.018), tg (p=0.024), tg/hdlc ratio (p=0.028), glycemia (p=0.004) and homa-ir (p=0.0014). male placed above the 50th p of alt had higher bmi (p=0.017) and tg/hdlc ratio (p=0.048), and above the 75th p had lower values of hdlc (p=0.042). only 16.5% of women and 14.5% of men, above the 75th p of alt, showed an increase in liver brightness in the echography. this work shows in woman an early association of alt with tg/hdlc ratio and homa-ir. since the last two are independent predictors of cardiovascular risk, attention should be drawn to alt values near the upper limit of the normal range even in the absence of nafld and obesity.