Gaucher's disease is a familial storage disease caused by a deficiency of the enzyme glucocerebrosidase. Pulmonary involvement is considered rare in Gaucher's disease, especially type I. Sporadic case reports have shown various types of lung involvement, but the spectrum of pulmonary pathology in Gaucher's disease has not been described. Nine cases of Gaucher's disease were retrieved from the autopsy file of Hadassah Medical Center, Jerusalem, Israel. There were six cases with type I Gaucher's disease and three cases with type II. Lung sections were evaluated, and special stains were employed, including immunohistochemical stains for CD68, cytokeratin, and CD34. Gaucher cells were found in the lungs in all nine cases. The involvement was considered pathologically significant in five of nine cases and clinically significant in three of nine cases. Four distinct patterns of pulmonary involvement by Gaucher cells emerged: intracapillary (9 of 9), patchy interstitial infiltrates in a lymphatic distribution (2 of 9), massive interstitial thickening of alveolar septa (1 of 9), and intra-alveolar infiltrates (2 of 9). The universal involvement of pulmonary capillaries indicates that this is probably systemic in nature and not intrinsic to the lungs. Pulmonary involvement in Gaucher's disease is commoner than previously recognized. Immunocytochemical stains help to identify isolated Gaucher cells and distinguish them from native alveolar macrophages.