ObjectiveTo summarize the clinical features of cytomegalovirus infection after severe pneumonia in immunocompetent subjects. MethodsTwo cases of cytomegalovirus infection after severe pneumonia in immunocompetent subjects were reported and the literatures were reviewed. ResultsTwo elderly patients were admitted to our Respiratory Intensive Care Unit for severe pneumonia and typeⅠrespiratory failure. After treatment of invasive mechanical ventilation, broad-spectrum antibiotics and steroids, their body temperature became normal with improvement of oxygenation and lung infiltrates on chest radiograph. After extubation, their oxygenation deteriorated, with extensive lung infiltrates on chest X ray. Coincidently, their blood cytomegalovirus DNA became positive and then they were treated with parenteral ganciclovir for more than 2 weeks. After that, their oxygenation and chest radiograph returned to normal. Combined with the results of the related literature, invasive mechanical ventilation and use of corticosteroids could be the risk factors of immunocompetent subjects to develop cytomegalovirus infection after severe pneumonia. The clinical characteristics include deterioration of oxygenation and extensive lung infiltrates without positive pathogenic findings of bacteria and fungi. Quantitive nucleic acid amplification tests for blood cytomegalovirus DNA, cytomegalovirus pp65 antigenemia test and histology/immunohistochemistry are recommended diagnostic tools. Valganciclovir or intravenous ganciclovir are recommended as first-line treatment for at least 2 weeks. ConclusionsCytomegalovirus infection occurs frequently in immunocompe-tent subjects with critical illness. Cytomegalovirus pneumonia should especially be considered in patients with severe pneumonia, receiving mechanical ventilation and steroids. Early diagnosis and treatment may help improve the prognosis of these patients.