Platelet-derived growth factors (PDGFs) have been implicated in the control of cell proliferation, survival and migration. Patch mutant mice harbor a deletion including the PDGF alpha receptor gene and exhibit defects of neural crest origin which affect pigmentation in heterozygotes and cranial bones in homozygotes. To verify the role of the PDGF alphaR gene during development, mice carrying a targeted null mutation were generated. No pigmentation phenotype was observed in heterozygotes. Homozygotes die during embryonic development and exhibit incomplete cephalic closure similar to that observed in a subset of Patch mutants. In addition, increased apoptosis was observed on pathways followed by migrating neural crest cells. However, alterations in mutant vertebrae, ribs and sternum were also observed, which appear to stem from a deficiency in myotome formation. These results indicate that PDGFs may exert their functions during early embryogenesis by affecting cell survival and patterning.