Bone morphogenic proteins (BMPs) constitute a group of multifunctional growth factors that belong to the transforming growth factor-beta (TGF-beta) family. During the last few years, the roles of BMPs, both in development and in specific adult tissues, have been extensively studied. One of such proteins, BMP4, has been identified as a key regulator in the development of mesoderm, and particularly, in the specification of the vascular and hematopoietic systems. BMP4 has also been found to be an important regulator of the growth of hematopoietic stem cells (HSC), participating in the control of their proliferation, expansion and differentiation. Herein, we present an overview on the different roles that BMP4 plays in mammal development, and in the regulation of hematopoiesis.