Summary: Severe pneumonia due to cytomegalovirus in chronic obstructive pulmonary disease. Introduction: We describe two cases of immunocompetent patients with chronic obstructive pulmonary disease (COPD) who developed severe cytomegalovirus (CMV) pneumonia. The clinical and radiological context and CMV replication in broncho-alveolar lavage suggested a diagnosis of CMV pneumonia. Case histories: We report two cases in patients with moderate chronic obstructive pulmonary disease not treated with long-term steroid therapy who developed bilateral pneumonia with hypoxaemia. The only pathogen identified was CMV with replication of the virus in the broncho-alveolar lavage. Investigation failed to detect any associated immune deficiency. Conclusion: Severe cytomegalovirus pneumonia could be encouraged by the existence of chronic obstructive pulmonary disease due to local inflammatory changes.