The purpose of this study was to quantitatively and qualitatively analyze the age-related histopathological changes of human palatine tonsil. As for specimens of total 118 tonsils, 52 palatine tonsils obtained at autopsy and 66 palatine tonsils obtained by tonsillectomy from patients with the diagnosis of chronic tonsillitis were used. Of these specimens, 71 were from male and 47 were from female, and the age ranged from 6 months to 89 years. The palatine tonsil was routinely sectioned longitudinal at its median, toward the tonsil hilus. 4 microns thick sections were prepared and then stained with hematoxylin-eosin, and according to the elastica-van Gieson staining method. The I-BAS one picture analyzer of ZEISS Co. was used to determine the areas covered with the parenchymal (lymphatic tissue) and extraparenchymal tissue (crypt, fibrous connective tissue and fatty generation) of the palatine tonsil. The results obtained are as follows; 1) The ratio of the parenchymal area to the total area of tonsils, in both specimens obtained at autopsy and tonsillectomy, decreased with age. 2) The average area of lymphoid follicles, in both specimens obtained at autopsy and tonsillectomy, decreased with age. 3) The number of lymphoid follicles per unit area, in both specimens obtained at autopsy and tonsillectomy, did not show any correlation with age. However, the number remarkably decreased in patients with the age of above 70. 4) The lymphocyte infiltration number per unit area of crypt epithelium, in both specimens obtained at autopsy and tonsillectomy, decreased with age. 5) The ratio of crypt area to the total area, in both specimens obtained at autopsy and tonsillectomy, did not show any correlation with age. However, increasing tendency with age was seen. 6) The ratio of fibrous connective tissue area to the total area for, in both specimens obtained at autopsy and tonsillectomy, increased with age. 7) Collagen fibers and elastic fibers, in both specimens obtained at autopsy and tonsillectomy, showed the tendency to proliferate with age. 8) Fatty degeneration was shown to begin in specimens of about 25 years old in age, and subsequently, was seen in most of specimens of above 35 years in age. Fatty degeneration tends to increase with age. The above results indicate that the parenchymal and extraparenchymal tissues of the palatine tonsil undergo both quantitative and qualitative changes with age.