Clinical and pathologic evidence for interstitial pulmonary fibrosis occurring in some patients with the Hermansky-Pudlak syndrome is well described in the literature, but data on immunologic mechanisms operating in this form of lung disease have not been published. In this case report, we describe bronchoalveolar lavage (BAL) findings in a patient with this syndrome. Recovered alveolar macrophages (AM) contained the characteristic ceroidlike material previously described in interstitial macrophages in pathologic specimens. The BAL analysis was similar to that seen in idiopathic pulmonary fibrosis, with increased levels of immunoglobulins and numbers of IgG and IgA secreting cells, and normal percentages of putative helper and suppressor T-cell subsets. In addition, superoxide production by stimulated AM was increased, possibly secondary to phagocytosis of the ceroidlike material. The lavage in this patient was compatible with a mild inflammatory process that was consistent with gallium scan results and the patient's clinical course.