The melanocortin peptides regulate a wide variety of physiological processes, including pigmentation and glucocorticoid production, and also have several activities in the central and peripheral nervous systems. The melanocortin receptor family includes the melanocyte-stimulating hormone receptor (MSH-R), adrenocorticotropic hormone receptor (ACTH-R), and two neural receptors, MC3-R and MC4-R. In the human these receptors map to 16q24 (MSH-R), 18p11.2 (ACTH-R), 20q13.2 (MC3-R), and 18q22 (MC4-R). The corresponding locations in the mouse are 8, 18, and 2; a variant for mapping MC4-R has not yet been identified. The data reported here also show that the neural MC3 receptor maps close to a disease locus for benign neonatal epilepsy in human and near the E1-2 epilepsy susceptibility locus in the mouse.