The purpose of this study was to evaluate the role 0 1' integrin a 3 and integrin ß 1 in the oral squamous cell ca rcinomas. For this study‘ 10 specimens diagnosed as squamous cell carcinoma referred to the Dept. of Oral Pathology. School of Dentis try, Kyung Hee Univers ity, and 5 specimens of normal oral mucosa without any inflammatory cha nges were used as experimenta l and co nt rol groups, respectively. AlI s pecimens; experirnental and control group were f ixed in neutral f ormalin so lu tion and embedded in paraffin, and then the serial tissue section were rnade 5i1m in thickness and processed for imrnunohi stochemical observatlon The specimens were incubated with prirnary antibody against integrin a 3 r integrin ß 1‘ each was diluted at 1;100, followed by the super sensit ive non- biotin horse r adish peroxidase detection sys tem with DAB as chromogen‘ After counters ta ining with Gill ’s hematoxylin stain method and mounted and examined under the light microscope. Based on the intens ity of the immunoreactivity, intensity of the immunity was scored no ep ithelial stain, weak 0 1' focal epitheli al sta in, modera te 0 1' focal intensive epithelial stain, intense genera lized epitheli al s taining for the e pithelia l, and co nnective ti ssue component in squamous cell carcinomas, and normal oral mucosa on each Expression of integrin a 3 in t he oral mucosa was negli gible. Expression 0 1' integrin a 3 in expression in the or al s mnus cell ca rcinoma was ve ry wea k, but the express ion was increased in poorly differ entiat ed type of the oral squamous cell carcinomas ln the oral mucosa , expression of in tegr in ß 1 ra nged from weak to moderate in the cytoplasm and the cell membra nes of the kera tini zed and basal cell layer. Nuclei were mainly integrin ß 1 negative‘ but rarely revealed weak expression. ln sq uamous cell carcinoma, expression of integrin ß 1 was ntense notably in the cytoplasm, cell membrane a nd nuclear membra ne Nuclei of several tumor cells revealed moderate expression of integrin ß 1. Expression of integrin ß 1 was increased the poorly diffe rentiated type of in squamous cell carcinoma compare to that in moderate or well diffe rentiated type of oral squamous cell carCllìoma These results suggest integrin a 3 and integrin ß 1 may be influ enced the development and growth of the squamous cell carcima .