Infectious and malignant disease processes are responsible for most pulmonary abnormalities seen in patients with acquired immunodeficiency syndrome (AIDS). There are, however, a number of noninfectious and nonmalignant disorders that can involve the lungs of these individuals. Nonspecific interstitial pneumonitis and lymphocytic interstitial pneumonitis may mimic opportunistic infections both clinically and radiographically. Congestive cardiomyopathy may develop and result in pulmonary edema. Other disorders such as alveolar proteinosis and desquamative interstitial pneumonitis are also reported. Bronchoalveolar lavage, a diagnostic technique frequently employed in AIDS patients, may itself produce pulmonary opacities. Knowledge of these disorders may aid in the evaluation of AIDS patients for whom an infectious etiology for pulmonary abnormalities cannot be found.