Viral infections are an extremely common and predictable problem in organ and hematopoietic stem cell transplant patients. Antiviral drugs given either prophylactically or as early therapy for patients detected to be shedding virus appears to be an effective strategy for reducing herpes virus infections. However, long-term treatment with these drugs is associated with significant toxicity, expense and the appearance of drug resistance virus isolates ultimately resulting in treatment failure. Over the last few years, there is increasing evidence that cellular immune therapies can reverse the outgrowth of lymphoid malignancies and can also provide therapeutic benefit against viral infections and solid cancers. While the expansion and adoptive transfer of virus-specific T-cells from the healthy original donor can be an effective strategy to control viral replication, this is not possible when donors are seronegative or are subsequently inaccessible. Recent studies have demonstrated the successful application of third-party “off-the-shelf” T cell therapies. These allogeneic T cell therapies show minimal toxicity and long term reconstitution of protective anti-viral immunity following their adoptive transfer back into the patients. More recently, we have also developed a single platform technology to extend this immunotherapeutic strategy for multiple pathogens. T cells directed towards multiple pathogens can be rapidly expanded and can be used for adoptive immunotherapy. Finally, in collaboration with Memorial Sloan Kettering Cancer Center and Atara Biotherapeutics, we are developing various lines of “off-the-shelf” T cell therapies which will be used for the treatment of various virus-associated cancers and autoimmune disorders. These T cell therapies will be combined with immune monitoring technology (e.g. QuantiFERON-CMVÒ) which will allow us to identify high risk patients who may develop virus-associated complications post-transplantation.