Mutations in either Msx or Dlx genes cause severe craniofacial malformations. Importantly, many of the defects associated with each mutation have significant overlaps and show a compromised fate of cranial neural crest (CNC) cells, suggesting that Msx and Dlx may work together to regulate CNC cells during craniofacial development. Objectives: to test the possible interaction between these two homeobox genes in vivo and to elucidate the biological significance of this interaction. Method: we generated Msx1-/-;Dlx5-/- embryos. Result: the double knockout embryos survived to full term but died perinatally with severe craniofacial abnormality. Interestingly, unlike in the Msx1-/- mutant, palatine shelves of the double knockout embryos were able to extend to the midline and completed palatal fusion. Morphological analysis confirmed that the cleft palate rescue was due to the restored palatal process of the maxilla. Conclusion: taken together, our finding indicates that the genetic interaction between Msx1 and Dlx5 may differentially regulate the fate of CNC cells during craniofacial development. Supported by R01 DE012711 and R01 DE014078, NIDCR, NIH.