Obesity is linked to a low-level chronic inflammatory state that may contribute to the development of associated metabolic complications. Retinol-binding protein 4 (RBP4) is an adipokine associated with parameters of obesity including insulin resistance indices, body mass index, waist circumference, lipid profile, and recently, with circulating inflammatory factors. Due to the infiltration of adipose tissue in obesity by macrophages derived from circulating monocytes and, on the other hand, the existence of a close genetic relationship between adipocytes and macrophages, we decided to examine if RBP4 is expressed in monocytes and/or primary human macrophages. While we did not detect expression of RBP4 in undifferentiated monocytes,