It was first established in the 1970s that the brain serotonin (5-HT) system was involved in the control of eating. Subsequent progress in the molecular pharmacology of 5-HT receptors, and the development of selective 5-HT receptor ligands, has clarified our understanding of the role of 5-HT in the regulation of ingestive behavior. Of the 14 5-HT receptor subtypes currently described, 5-HT1A, 5-HT1B and 5-HT2C receptors have been of principal interest in the regulation of food intake. This is largely due to the development of suitable agonists, antagonists and gene-knockout animals with which the role of these receptors can be elucidated. The recent development of selective ligands and knockout mice for other 5-HT receptors, including the 5-HT2B and 5-HT6 receptors, has also suggested a role for these receptor subtypes in eating behavior. Studies using such approaches should further our understanding of the role of serotonin in the regulation of feeding behavior and thus, may lead to the development of novel, safe, serotonin receptor ligands for the treatment of obesity.