The bone morphogenetic protein (BMP) family consists of several growth factor proteins that belong to the transforming growth factor-β (TGF-β) superfamily. BMPs bind to type I and type II serine–threonine kinase receptors, and transduce signals through the Smad signalling pathway. BMPs have been identified in mammalian ovaries, and functional studies have shown that they are involved in the regulation of oogenesis and folliculogenesis. This review summarizes the role of the BMP system during formation, growth and maturation of ovarian follicles in mammals.