To study the relationship between asthma and bronchial hyper responsiveness(BHR).The reactivity of bronchi to inhalation of methacholine, the plasma levels of substance P(SP),soluble P selection (sP selectin),vasoactive intestinal peptide(VIP), and fibronectin(Fn) were assessed in 68 cases of asthma, 62 patients with cough variant asthma(CAV), and 43 healthy subjects.It was showed that the tests of airway reactivity were all positive in 68 cases of asthma and 62 cases of CVA.Dmin in asthma and CVA was(8 81?9 67)u and(5 97?4 37)u,respectively,in these two groups of patients. Dmin in asthma patients was higher than in CAV patients ( P