Integrins have been shown to play important roles in embryonic development, wound healing, metastasis, and other biological processes. αvβ5 is a receptor for RGD-containing extracellular matrix proteins that has been suggested to be important in cutaneous wound healing and adenovirus infection. To examine the in vivo function of this receptor, we have generated mice lacking β5 expression, using homologous recombination in embryonic stem cells. Mice homozygous for a null mutation of the β5 subunit gene develop, grow, and reproduce normally. Keratinocytes harvested from β5−/− mice demonstrate impaired migration on and adhesion to the αvβ5 ligand, vitronectin. However, the rate of healing of cutaneous wounds is not different in β5−/− and β5+/+ mice. Furthermore, keratinocytes and airway epithelial cells obtained from null mice show adenovirus infection efficiency equal to that from wild-type mice. These data suggest that αvβ5 is not essential for normal development, reproduction, adenovirus infection, or the healing of cutaneous wounds.