Exoenzyme Y (ExoY) is a Pseudomonas aeruginosa toxin that is introduced into host cells through the type 3 secretion system (T3SS). Once inside the host cell cytoplasm, ExoY generates cyclic nucleotides that cause Tau phosphorylation and microtubule breakdown. Microtubule breakdown causes inter-endothelial cell gap formation and tissue edema. While ExoY transiently induces inter-endothelial cell gap formation, it remains unclear as to whether ExoY prevents repair of the endothelial cell barrier. Here, we test the hypothesis that ExoY intoxication impairs recovery of the endothelial cell barrier following gap formation, decreasing migration, proliferation, and lung repair. Pulmonary microvascular endothelial cells (PMVECs) were infected with P. aeruginosa strains for six hours, including one possessing an active ExoY (PA103 exoUexoT::Tc pUCPexoY; ExoY⁺), one with an inactive ExoY (PA103exoUexoT::Tc pUCPexoY^K81M; ExoY^K81M), and one that lacks PcrV required for a functional T3SS (PcrV). ExoY⁺ induced inter-endothelial cell gaps, whereas ExoY^K81M and PcrV did not promote gap formation. Following gap formation, bacteria were removed and endothelial cell repair was examined. PMVECs were unable to repair gaps even 3-5 days after infection. Serum-stimulated growth was greatly diminished following ExoY intoxication. Intra-tracheal inoculation of ExoY⁺ and ExoY^K81M caused severe pneumonia and acute lung injury. However, whereas the pulmonary endothelial cell barrier was functionally improved one-week following ExoY^K81M infection, pulmonary endothelium was unable to restrict the hyperpermeability response to elevated hydrostatic pressure following ExoY⁺ infection. ExoY is an edema factor that chronically impairs endothelial cell barrier integrity following lung injury.