Background: Cytomegalovirus (CMV) infection has been associated with venous thromboembolism (VTE) and acute coronary syndromes (ACS). Methods: A retrospective study was conducted within the OSF HealthCare System in Peoria, Illinois. The objectives were to determine the incidence of acute VTE and ACS within one year of CMV testing. The “study group” included patients with positive CMV IgM or positive CMV Polymerase Chain Reaction (PCR). The “seropositive control” group included patients with positive CMV IgG and negative IgM. The “seronegative control” group included patients with negative CMV IgG and IgM, or negative PCR. Results: Within one year of CMV infection, 38 of 379 patients (10.0%) developed VTE in the study group compared to 41 of 1334 patients (3.1%) in the seropositive control and 37 of 1249 (3.0%) in the seronegative control. Adjusting for age and gender, both control groups were less likely to have VTE than the study group within one year (Seropositive Control: OR = 0.3, 95% CI 0.2-0.5, p <0.0001; Seronegative Control: OR = 0.4, 95% CI 0.2-0.6, p <0.0001). ACS was more likely to occur in the study group, with incidence of 7.7% compared to 4.7% (p <0.0001) in the seropositive control and 1.9% (p <0.0001) in the seronegative control. Adjusting for age and gender, the seronegative control was less likely to develop ACS than the study group within one year (OR = 0.4, 95% CI 0.2-0.7, p = 0.003). Conclusions: This retrospective study demonstrates that CMV infection may be a significant risk factor for VTE and ACS.