Objective It is currently considered that the defect of mitotic spindle caused by centrosome abnormalities may be one of the reasons for the development of aneuploidy in tumors. This study attempted to elucidate the possible role of centrosome defects in the development and progression of OSCC by investigating the frequency of centrosome amplification in oral precancerous lesions and OSCC.Methods Formalin-fixed, paraffin-embedded tissues of 12 cases of normal oral epithelium, 22 case of dyspla- sia with different degree epithelium dysplasia and 32 cases of OSCC with different differentiation were investigated for centrosome status by using indirect Immunofluorescence double staining with antibodies to centrosome protein gamma-tubulin and cytokeratin. The differences and the change trend of centrosome status in these groupswere statistical analyzed by SPSS10·0.Results Normal oral epithelium showed normal centrosomes in epithelium cells, while 16 of 22 cases (72·73%) of dysplasia(DYS) and 27 of 32 cases (84·38%) of OSCC showed the evidence of centrosome amplification and morphological abnormalities characterized by huge size, clump or supernumerary centrosomes in a fraction of epithelium ortumor cells. The percentage of cellswith abnormal centro- somes increased gradually from mild-dysplasia epithelium to poorly differentiated OSCC, which positively correlated with the histo- logicalcytologic grade of oral precancerous lesions and OSCC(P