The morphological expression of the immune response of palatine tonsils obtained from patients with pustulosis palmaris et plantaris (PPP) was investigated by morphometry in conjunction with immunohistochemistry. First, to differentiate the histological features of tonsils between PPP and habitual tonsillitis, each extent of the T cell dependent areas (T nodules), B cell dependent areas (lymph follicles), germinal centers, mixed areas of T cells and B cells, and lacunar epithelium was measured and compared on 38 patients with PPP and 47 with habitual tonsillitis, respectively. The most remarkable findings in PPP were enlargement of the secondary T nodules, and atrophy of the lymph follicles with a decrease in number of the germinal center cells and fibrosis. These changes of lymph follicles were similar to those in the older patients with habitual tonsillitis, which suggests the intensely advanced stage of the immune response within the tonsils. Second, the histological structures of the tonsils of 15 tonsillectomy effective cases (88.2%) was compared with those of two non-effective cases in curing skin lesions. The histological structure in the non-effective cases was very similar to that in habitual tonsillitis cases. This indicates that the histological findings may be useful in predicting the effects of tonsillectomy on PPP.