Given its potential role in metabolic syndrome, criteria of this entity and serum adiponectin levels, the present investigation was realized to evaluate the role of the SNP rs17300539 in the ADIPOQ gene and its relationships with obesity, metabolic syndrome, and serum adiponectin levels in a population of Caucasian out patients with obesity received in an Obesity UNit. This evidence concerns the gene ADIPOQ and obesity due to melanocortin 4 receptor deficiency.