Although various elements of the immune system are involved in detection and elimination of neoplastic cells, immune surveillance mechanisms are not always successful in eradicating cancer. Invariant natural killer T cells are potent immunomodulatory lymphocytes that secrete large amounts of Th-1 and/or Th-2 cytokines in response to glycolipid agonists. The observed role of invariant natural killer T cells in ANTITUMOR IMMUNITY in various animal models and the relatively recent identification and availability of Invariant natural killer T cell glycolipid ligands with anticancer properties such as Α-GALACTOSYLCERAMIDE have led to several invariant natural killer T cell-based clinical trials in cancer patients with somewhat promising outcomes. The objective of this article is to provide a short overview on immunobiology of invariant natural killer T cells followed by their potential applications in treatment of cancer.