A man with serologic evidence of HIV infection and a depressed T-helper:suppressor ratio developed fever, pulmonary infiltrates, and respiratory failure. Bronchoalveolar lavage and transbronchial biopsy failed to reveal an infectious cause; however, an open lung biopsy demonstrated classic bronchiolitis obliterans organizing pneumonia. The patient responded completely to corticosteroids. To the best of our knowledge, this represents a previously undescribed and readily treatable cause of respiratory failure in patients with HIV infections.