The changes of cytosolic free calcium in the peripheral neutro-phils after the rabbits were exposed to smoke inhalation were observed and the ptherapeutic effects of tetrandrine-a calcium antagonist?on the level of free calcium and on the injury also studied.It was found that the number of neu-trophils increased significantly in the peripheral blood after a transient drop and it also increased in the bronchoalveolar lavage fluid.The level of free calcium in the neutrophils were increased at the same time.Tetrandrine could reduce the number of neutrophils in the lungs,the calcium level in the neutrophils,and the severity of inhalation injury.The findings suggest that there is a close relationship between the activation of neutrophils and the pathophysiological manifestations of smoke inhalation injury,and tetrandrine can exert certain therapeutic effects on smoke inhalation injury through reducing the level of cytosolic free calcium in the neutrophlis to modulate their functions