This study investigated the significance of detecting cytomegalovirus in the bronchoalveolar lavage fluid of patients with human immunodeficiency virus infection. Bronchoscopy with BAL was performed on all patients. Lavage was examined for CMV by cytology, culture, and immunofluorescence. The lavage results were compared to clinical status at the time of bronchoscopy and the outcome of the respiratory event. Cytomegalovirus was detected in 51 percent of the BALs in the patients with HIV infection and 25 percent of the immunosuppressed patients without HIV. No association was found in the HIV infected patients between CMV and hypoxemia, abnormal chest roentgenogram, leukopenia, and increased mortality. As indicated by mortality, CMV did not significantly increase the severity of Pneumocystis carinii pneumonia. The study also suggested that CMV in BAL fluid reflected bronchopulmonary replication of the virus, and not contamination by virus in the blood. Cytomegalovirus does not appear to contribute directly to the pulmonary disease found in most patients with HIV infection.