Considerable progress has been made in our understanding of the immunobiology of infections in immunocompromised hosts. Insights derived from animal model and human studies have provided the rationale to investigate immunotherapy with alphabeta+ T cells to restore responses considered essential for protective immunity to cytomegalovirus infection. Future studies will address the role of adoptive immunotherapy using different immunoeffector cell populations to improve control of virus infection. The use of genetically modified T cells has already been evaluated clinically and offers the potential for improving safety and efficacy and removing obstacles to successful immunotherapy. Although these studies are in the early stages and present considerable technical challenges, the results suggest that cellular immunotherapy will be a fruitful area for investigation in future years.