Fatty acid-binding protein, adipocyte, also known as Adipocyte-type fatty acid-binding protein, Fatty acid-binding protein 4, Adipocyte lipid-binding protein, and FABP4, is a cytoplasm protein which belongs to the calycin superfamily and Fatty-acid binding protein (FABP) family. In familial combined hyperlipidemia (FCHL), FABP4 correlated to body mass index (BMI), waist circumference and homeostasis model assessment (HOMA) index.FABP4 levels were associated with triglyceride-rich lipoproteins. In humans serum FABP4 levels correlate significantly with features of PCOS. It appears to be a determinant of atherogenic dyslipidemia. FABP4 pathway mediates the sebaceous gland hyperplasia in keratinocyte-specific Pten-null mice. FABP4 concentration significantly increased with an increasing of MS features and was strongly correlated with body-mass index, triglycerides, HDL-cholesterol concentrations and blood pressure. Patients in the highest quartile of FABP4 presented a six-fold increased odds ratio for MS and a three-fold increased odds for LD, adjusted by age, sex, body-mass index and the antiretroviral therapy. FABP4 is a strong plasma marker of metabolic disturbances in HIV-infected patients, and therefore, could serve to guide therapeutic intervention in this group of patients.