Studies of experimentally mucosal allergic reaction of the epipharynxwall, changes of local alkali phosphatase through the Shwartzman's phenomenon and effect of diphtheria toxin injection into epipharynxwall on general organs were carried out in rabbits for the purpose of clarifying the mechanism of “Epipharynx syndrome and symptom (Yamasaki).”1) The Shwartzman's phenomenon on mucous membranes of the epipharynx;14 albino male rabbits weighted about 2kg were divided into 2 groups. The first group (10 rabbits) were initially injected with 0.2cc of prodigiosus culture filtrates into both mucous membranes of the epipharynx and buccal mucous membranes, and then 24hours later were injected intravenously with 2cc of the same filtrates. The second group (4 rabbits) were done only the former proceedures as a control. The following results were obtained.A severe hemorrhagic reaction was seen in all 10 rabbits of the first group and hyperemia was seen in 1. out of 4 rabbits of the control group at injected mucous membranes of the epipharynx, but no reactions were observed in both groups at injected buccal area.Histological findings of the Shwartzman's reactions area of the epipharynx were remarkably similar to those noted in skin reaction. A severe hemorrhagic reaction with necrosis observed in submucous tissue was mainly due to rupture of the blood vessels below the surface and fibrinous thrombosis was frequently observed. Infiltrations of polynucleic leucocytes were preferably few.2) Changes of local alkali phosphatase through the Shwartzman's phenomenon;Immediately before the Shwartzman's reactive injection, adrenalin, pilocarpin or atropin was injected into one side of the epipharynx wall of each rabbit and then various degree of local skin reaction was able to be obtained. Male albino rabbits were dissected 6 hours after injection of the various vegetative posions and local alkali phosphatase in abdominal skins where the Shwartzman's phenomenon was seen, was measured after Gomori-Takamatsu's methode.Local alkali phosphatase was appeared to be increased according as hemorrhagic reaction was marked to be stronger.3) Effect of diphtheria toxin injection into mucous membranes of the epipharynx on general orgns.On male albino rabbits injected with 0.5cc of diphtheria toxin (L. F, 85 unit) into mucous membranes of the epipharynx and dissected immediately after injection, histological observations of submaxillary glands, lungs, suprarenal bodies and kidneies were made.As a control, same proceedures were done on rabbits dissected immediately and 3 hours after injection into subcutaneous tissue.In cases injected into the epipharynx and dissected immediately after injection, histological changes were noted most remarkablly in contrast with cases injected into subcutaneous tissue and dissected immediately after injection, which were found few histological lesions.In cases injected into subcutaneous tissue and dissected 3 hours after injections, these changes were moderate. Amongs observed organs, suprarenal bodies showed most marked hypertrophy and hemorrhagic reaction with necrosis in fascicular zone.The Author presumes that mucous membranes of the epipharynx wall are very sensitive to local reaction such as the Shwartzman's phenomenon and mucosal reaction of the epipharynx is closely related with generalized effect.