Specimens from premortem pulmonary cytology, transbronchial biopsy, and autopsy were studied in 11 patients with acquired immunodeficiency syndrome who developed pulmonary cryptococcal disease. Nine of 11 patients had culture-proved cryptococcal meningitis. Extremely low T-cell helper/suppressor ratios (mean, 0.12) were observed in seven of 11 patients. In six of eight patients, transbronchial biopsy specimens showed a characteristic interstitial pattern with yeasts in the alveolar septae, minimal cellular inflammation, and no well-formed granulomas. On cytologic examination, organisms were present in seven (100%) of seven cell blocks and five (83%) of six smears prepared from the bronchoalveolar lavage, and in five (63%) of eight bronchial brushings. Small, poorly encapsulated yeast forms were sometimes present, requiring mucicarmine and acid mucopolysaccharide stains for confirmation of the diagnosis of pulmonary cryptococcosis. Overall, bronchoscopy yielded a diagnosis in seven of eight patients. At autopsy, two of five patients demonstrated an interstitial pattern of infection in all lobes of the lung with marked pleural thickening and giant-cell formation; two other patients showed mixed interstitial and intra-alveolar cryptococcal infiltrates. Nodal and disseminated infection were present in four patients. In patients with acquired immunodeficiency syndrome who have cryptococcal meningitis, pulmonary cryptococcal disease is common and must be distinguished from other opportunistic infections.