Abstract: Purpose and Methods : The incidence of micronucleated cells in exfoliated oral mucosa cells and the in2 cidence of micronucleated cells and chromosome aberration in peripheral blood lymphocytes of 54 smoking oral leukoplakia patient s were examined. Results : The result s showed that the incidence of micronucleated cells in exfoliated oral mucosa cells , the incidence of micronucleated cells and chromosome aberration in peripheral blood lymphocytes of smoking oral leukoplakia patient s were significantly higher than those of healthy persons ; the in2 cidence of micronucleated cells in exfoliated oral mucosa cells of lesion mucosa had a positive correlation with the degrees of oral lesions , and the incidence of micronucleated cells in exfoliated oral mucosa cells of normal mucosa had a positive correlation with the incidence of micronucleated cells in peripheral blood lymphocytes. Conclu2 sion : It is concluted that the incidence of micronucleated cells in exfoliated oral mucosa cells of lesion mucosa may reflect the degrees of oral lesions , and it is simple and economical to use the incidence of micronucleated cells in exfoliated oral mucosa cells of normal mucosa to substitute peripheral blood lymphocytes in reflecting DNA damage levels of body exposure to carcinogens.

Key words: Oral leukoplakia, micronuclei, chromosome aberration