Viral infections remain a major cause of morbidity and mortality after pediatric hematopoietic stem cell transplantation. Adoptive transfer of donor-derived virus-specific T cells can reconstitute antiviral immunity in recipients and be effective both in preventing and treating cytomegalovirus, Epstein-Barr virus and adenovirus infection. Current efforts are focused on providing protection toward a broader range of viruses safely, rapidly and effectively.