Adipocyte fatty acid binding protein (A-FABP) has been suggested as playing an important role in the pathogenesis of metabolic syndrome. The aim of this study was to evaluate serum A-FABP as a marker of metabolic syndrome and to assess its predictive accuracy in a Caucasian population. Anthropometric and serum analyses were performed for body mass index (BMI), waist circumference, A-FABP, insulin, triglycerides, total cholesterol, high-density lipoprotein-cholesterol (HDL-c), low-density lipoprotein-cholesterol (LDL-c), uric acid, and glucose on 67 non-obese, healthy subjects and 71 subjects with metabolic syndrome. Quicki-quantitative insulin sensitivity check index, receiver operating characteristic curve (ROC-curve) and chi(2) analysis were completed. Compared with healthy controls, subjects with metabolic syndrome had a significantly higher A-FABP serum level (mean: 42.4 vs. 23.7 microg L(-1); P < 0.01). The A-FABP serum level correlated with fasting levels of insulin (r = 0.34; P < 0.01), glucose (r = 0.21; P = 0.01), triglycerides (r = 0.4; P < 0.01), BMI (r = 0.57; P < 0.01) and waist circumference (r = 0.51; P < 0.01), but negatively with HDL-c (r = -0.23; P < 0.01) and Quicki (r = -0.32; P < 0.01). The relationship was defined between serum A-FABP level and metabolic syndrome diagnosis with 40% sensitivity and 99% specificity at A-FABP level 16.4 microg L(-1). Serum A-FABP level might be an independent marker of metabolic syndrome in a Caucasian population.