Varicella zoster virus behaves differently from other herpes viruses as it differs from them in many aspects. Recently, there has been growing evidence on the beneficial effects of the virus in immune compromised hosts and these effects are translated into prolongation of survival. The reported beneficial effects of the virus include: (1) stimulation of bone marrow activity in patients with hematologic malignancies and bone marrow failure syndromes, (2) antitumor effects in various hematologic malignancies and solid tumors, and (3) association with graft versus host disease which has anticancer effects. Additionally, there are several reports on the safety of the live-attenuated even in severely immune suppressed individuals and on the emerging role of the virus in cancer immunotherapy. In this review, the following aspects of the virus will be thoroughly discussed: (1) new data on the genetic background, pathogenesis, vaccination, and new therapeutic modalities; (2) bone marrow microenvironment and hematopoiesis; (3) cells involved in the pathogenesis of the virus such as: mesenchymal stem cells, dendritic cells, natural killer cells, T-cells and mononuclear cells; (4) cellular proteins such as open reading frames, glycoproteins, promyelocytic leukemia protein, chaperons, and SUMOs; (5) extracellular vesicles, exosomes, and micro-RNAs; and (6) signaling pathways, cytokines, and interferons.