Lung tissue obtained from 340 necropsies of persons aged 80 years and over was investigated for the occurrence of pulmonary amyloid deposits by means of a sensitive fluorescence technique. The incidence of pulmonary amyloidosis was about 2% below the age of 80, nearly 10% in individuals between 80 and 84 years, and more than 20% at and beyond 85 years. Vascular and concomitant alveolar-septal amyloidosis was seen slightly more often than the pure septal form of senile amyloidoisis. The two modes of deposition correspond to two different forms of cardiac amyloidosis, vascular and nodular. On the other hand, the two different modes of pulmonary amyloidosis affect different age groups. It is postulated that the disorder is related to age-linked immunological disturbances and to genetically determined factors.