Patients with known lymphoma frequently present with pulmonary abnormalities that require prompt diagnosis. The usual chest radiograph and bacteriologic studies often fail to be of diagnostic value. Since February 1973, we have performed flexible fiberoptic bronchoscopies on 76 patients with Hodgkin and non-Hodgkin lymphoma who presented with pulmonary abnormalities. Biopsy specimens revealed lymphoma in 21 of these 76 patients, pneumocystic carinii infection in six, aspergillus infection in three, and cryptococcus, herpes simplex, and squamous cell carcinoma, respectively, in the remaining three. In all, specific diagnosis was obtained in 33 patients (43%). One death from bleeding occurred in a patient with marked thrombocytopenia and respiratory failure. Flexible bronchoscopy is recommended as a valuable, relatively risk-free procedure in the diagnosis of the pulmonary manifestations, or complications, of lymphoma.