Pigment epithelium-derived factor (PEDF) is a 50 kDa secreted glycoprotein that belongs to the non-inhibitory serpin family group. PEDF has been described as a natural angiogenesis inhibitor with neurotrophic and immune-modulation properties; it balances angiogenesis in the eye and blocks tumor progression. The mechanisms underlying most of these events are not completely clear; however, it appears that PEDF acts via multiple high affinity ligands and cell receptors. In this review article, we will summarize the current knowledge on the biochemical properties of PEDF and its receptors, the multimodal activities of PEDF and finally address the therapeutic potential of PEDF in treating angiogenesis-, neurodegeneration- and inflammation-related diseases. J. Cell. Biochem. 106: 769–775, 2009. © 2009 Wiley-Liss, Inc.