The biological function of vitamin A for defense and suppresion of inflammation induced by varied causes has been investigated with respect to consumption of the vitamin A, and decrease in eicosanoid productions. In clinical study, it was observed that elevation of α_1-acid glycoprotein (AGP) and C-reactive protein (CRP), which are the acute phase reactants, closely related with decrease in vitamin A, RBP and prealbumin (PA) in patient with lower respiratory infection and mucocutaneus lymph node syndrome (MCLS). In rats, it was verified that absorption of vitamin A from the gut and its release from the liver were not suppressed by inflammation induced by burn injury and hypodermoclysis with terpene oil, and then, in the in vitro and in vivo studies, the enhanced consumption of vitamin A would be assumed under the condition accompained by inflammation. In additon, vitamin A suppressed the production of leukotrienes in macrophages from rat lungs after the stimulation with an endotoxin. These findings suggest that vitamin A deprevation is susceptible to infection due to increased production of leukotrienes.