In order to study the effects of mechanical strain on distribution of integrins in normal human pulmonary epithelial cell line H727, a cyclic strain unit in vitro was set up, and the redistribution of α₃,α₅,β₁ integrin in H727 cells subjected to 24 h cyclic strain was analyzed. Human pulmonary epithelial H727 cells seeded on either fibronectin or collagen Ⅳ surfaces were subjected to 15% elongation at a frequency of 40 cycles/min. Confocal microscopy revealed that α₃,α₅,β₁ integrin in H727 cells were concentrated and brighter,and cells created a large fusion of focal adhesion or adhesion plaques after 24 h exposure to strain. Under static condition, α₃,α₅,β₁ integrin in H727 cells maintained a diffuse pattern with an occasional speckle concentration in some regions. Furthermore α₃,α₅,β₁ integrin in H727 cells transferred from the apical layer to the basal layer and created adhesion plaques, and affinity between integrins and extracellular matrices(ECM) was enhanced. It is concluded that the formation of effective focal contacts is the concerted interaction between receptors recruitment and ligand occupy. This interaction plays an important role in transducing mechanical stimuli into intracellular signals.