Abstract The present study demonstrates that hypoxia activates a novel T cell-mediated mechanism of neovascularization triggered by VEGF in which p66Shc acts as the master regulator. Immune cells play an important role in the onset of angiogenesis. Here, we report that VEGF represents the major proangiogenic factor expressed by T cells exposed to hypoxia, a common feature of inflammation and tumor microenvironment. The supernatants of hypoxic T cells were highly angiogenic when delivered on the chick embryo CAM. The angiogenic response was abrogated by a neutralizing anti-VEGF antibody and mimicked by rVEGF. Interestingly, VEGF induction by hypoxia was up-regulated in Jurkat T cells overexpressing the adaptor protein p66Shc but not the inactive S36 p66Shc mutant, and it was abolished in p66Shc−/− mouse splenocytes. Accordingly, the angiogenic response induced by the supernatants from hypoxic p66Shc−/− splenocytes was reduced dramatically when compared with the wild-type controls. In conclusion, hypoxic T cells may contribute to the onset of angiogenesis through a novel VEGF-mediated mechanism, where p66Shc acts as a positive regulator.