Lung transplantation is a therapeutic option for end stage lung diseases. One of the most important topics in transplant management is the role of viral infections in chronic lung allograft dysfunction (CLAD) and in particular in acute rejection (AR). This review arise from a recent study BY Brideaux et al. that offers the opportunity to investigate deeply the incidence, risk factors, symptomatology and clinical outcome of respiratory viral infections. Although most respiratory viral infections cause self-limited upper respiratory diseases, lung transplant recipients (LTRs) are particularly prone to develop complications. The absence of symptoms is a pivotal problem in managing these patients as it can depend on absence of active replication or on the effect of immunosuppressive regimen. In one word viruses can be just passengers or aggressive drivers in a facilitated environment, and the potential damage is completely different, as the management. PCR samplings give us an idea of the presence but not the certainty of the activity of viruses, and this is another common problem in reading data. In Herpes Virus infections this problem can be overtaken by studying biological samples and immune response, balancing the presence (PCR) and the activity (shell vial) of viruses with specific immune response (elispot). In fact viral presence doesn't mean activity and activity doesn't mean pathology in case of competent immune response. All these data can be matched in every single patient and managed by a tailored approach, either monitoring or treating.