Leptin is a novel biomarker which is associated with milk production traits in dairy cattle. Leptin may prove to be most useful to animal producers as a stimulant for growth as well as reproductive traits or as a molecular marker to genetically select high performing individuals, ultimately with an aim to have higher production. Genetic polymorphisms in the intronic and exonic region of leptin gene reported are associated with productive and reproductive traits in cattle and this sort of genetic information can be used efficiently in breeding and management decisions. This monograph describe on the various aspect of bovine leptin gene in terms of molecular structure, mechanism of action, expression profile, polymorphic studies on leptin gene as well as the role of leptin for regulation of dairy milk production.