Vγ9Vδ2 T cells are important effector cells that may play a role in the anti-tumor immune response. Their capability to exert MHC-nonrestricted lytic activity against different tumor cells in vitro and their detection among tumor infiltrating lymphocytes in a variety of human cancers have supported the development of Vγ9Vδ2 T cell-based immunotherapy in the context of novel treatment against cancer. Accordingly, promising reports from recent clinical trials support the use of V γ9Vδ2 T cells as immunotherapeutic agents, either via adoptive transfer of ex-vivo expanded V γ9Vδ2 T cells or in vivo activation of V γ9Vδ2 T cells with compounds such as phosphoantigens or aminobisphosphonates. In this study we have performed a meta-analysis to assess the objective efficacy and safety of V γ9Vδ2 T cell-based immunotherapy. Database including Pubmed, Web of Science and SCOPUS were investigated to identify relevant studies. Thirteen clinical trials involving patients with advanced or metastatic cancer were selected. In order to estimate the strength of association between V γ9Vδ2 T cell-based immunotherapy and favorable clinical effect or toxicity grade we used event rate (ER) with 95 percent confidence interval (CI). The total effective rate provided significant results (ER = 0.407; P <0.014) while no correlation was found between serious adverse effects and Vγ9Vδ2 T cell-based therapy. This meta-analysis demonstrates that Vγ9Vδ2 T cell-based immunotherapy improves overall survival and, in view of its low toxicity grade, provides a proof of principle for its utilization as adjuvant to conventional therapies for resistant/refractory patients care.