It has been suggested that cytomegalovirus (CMV) infection may be associated with thrombosis in immunocompromised patients. In addition, an association between CMV infection and thrombotic events in immunocompetent hosts has been sporadically reported. We report on 1 immunocompromised and 8 immunocompetent adults who were admitted to a tertiary medical center and experienced a venous thromboembolic event during CMV infection. None reported previous thromboembolic events. All patients were diagnosed as suffering from acute CMV infection. Seven of the patients had vein thromboses. Significant additional thrombophilia was identified in 5 patients; 1 had 15.3 U/mL anti-cardiolipin IgM antibodies (elevated >7), 2 others were not evaluated for genetic procoagulant tendency. The exact nature of the procoagulant effect of CMV has not yet been clarified. Even though these mechanistic studies are incomplete, we suggest that from the clinical perspective, the presence of CMV infection should be considered a possible risk factor for thrombophilia, justifying a high index of suspicion for possible thrombotic events and subsequent decisions regarding prophylactic anticoagulation.