A 19-year-old white man with multiple recurrences of respiratory papillomatosis was admitted for recurrent left lower lobe pneumonia and lung abscesses. He was found to have a single large laryngeal papilloma, widespread bronchial papillomatosis, and large cavitary lesions of the left lower lobe. A lobectomy was performed. The smooth-walled, squamous-lined cavities contained large numbers of papillomas, which were strongly positive for human papillomavirus type 11 by in situ DNA hybridization. Findings of evaluation of the patient's humoral and cell-mediated immunity were within normal limits. Cavitation appears to have resulted from bronchial obstruction, postobstructive pneumonia, and liquefactive necrosis. We speculate that squamous metaplasia allowed the continued proliferation of papillomavirus within the cavities.