The clinical and histopathologic features of pulmonary amyloidosis were reviewed in 22 patients with systemic amyloidosis who came to autopsy. Eleven of 12 patients (92 percent) with primary amyloidosis had prominent interalveolar amyloid deposits. Symptoms attributable to these deposits were found in four cases (33 percent), while severe lung involvement was the apparent cause of death in one. Extensive deposition was noted in all three cases of amyloidosis associated with multiple myeloma or Waldenstrom's macroglobulinemia. Five of seven patients (71 percent) with secondary amyloidosis showed histologic lung involvement, which was perivascular or tracheobronchial in location, but not associated with symptoms. Histologic lung involvement is frequent in all forms of amyloidosis and lung tissue obtained from any patient with unexplained interstitial or reticular-alveolar pulmonary disease should be stained with Congo-red and viewed for green birefringence under polarizing microscopy for the presence of amyloid.