Infection with Cytomegalovirus (CMV) is very common among the adult population, with a prevalence of 50-90%, varying according with age, country and socioeconomic status. Although its presentation in immunocompetent adults is usually mild and a self-limited flu-like syndrome is often the rule, the immunocompromised patients are quite vulnerable, as this herpes virus can significantly increase the morbidity and mortality among them. CMV infection has been linked with thromboembolic events not only in this subgroup of patients, but also in otherwise healthy adults.