Mammalian cell receptors that promote entry of intracellular bacteria into nonphagocytic cells have not been identified. We show here that multiple members of the integrin superfamily of cell adhesion receptors bind the Y. pseudotuberculosis invasin protein prior to bacterial penetration into mammalian cells. Affinity chromatography of crude detergent extracts demonstrated that integrins containing the subunit structures α₃β₁, α₄β₁, α₅β₁, and α₆β₁ bound to immobilized invasin. Furthermore, phospholipid vesicles containing isolated integrin proteins were able to attach to invasin. Specificity for invasin binding to the identified integrin receptors was also demonstrated, as immunoprobing and phospholipid reconstitution studies showed that the α₂β₁ integrin, β₂ chain integrins, and vitronectin receptor (α_vβ₃) were not involved in cellular attachment to invasin.