Angiogenesis is a multistep process that involves  proliferation and migration of endothelial cells (ECs) and generation of extracellular matrix. Angiogenesis is regulated by multiple positive-  and negative-regulatory factors. Astrocytes,  whose  endfeet encircle neural capillaries, produce angiogenesis-modulating factors, and together with ECs, play a key role in forming and maintaining the blood-brain-barrier (BBB). It has been suggested  that closure of the BBB is correlated to  maturation of astrocytes. Recently we found that bone morphogenetic protein type I receptor (BMPRIA) in astrocytes played a critical role in interactions between ECs and astrocytes to form a functional BBB. Here we review the latest  advances in our understanding of the astrocytic bone morphogenetic protein (BMP) signaling mechanism of action and its in vivo functions.