Placental growth factor (PLGF) is a member of the VEGF (vascular endothelial growth factor) sub-family - a key molecule in angiogenesis and vasculogenesis, in particular during embryogenesis. The main source of PLGF during pregnancy is the placental trophoblast. PLGF is also expressed in many other tissues, including the villous trophoblast.

PLGF is a dimeric glycoprotein that, like VEGF, can bind with high affinity to the tyrosine kinase receptor vascular endothelial growth factor receptor 1 (VEGFR-1/Flt-1). PLGF/VEGF heterodimers have been isolated and shown to bind also to the VEGFR-2/KDR/Flk-1 receptor the major mediator of VEGF activities.PLGF shares approximately 42% amino acid (aa) sequence identity with VEGF (53% within the PDGF region), and the two proteins share significant structural similarity.