<正> 480 patients with 1019 Leukoplakic lesions were studied and followedup for 5 years

none of them had malignant changes.Among the 401 smo-kers 385（96.01%）had smoking habit for 11 years.Method of odds ratiowas used for analysis

and it was found that the lesions in both smokersand non-smokers could“regress”but 3 times more in the latter than inthe former.“Aggravated cases could be seen in both smoking and non-smok-ing groups but their difference was not significant.“New lesion”

werefound in both groups too

but more than 3 times in the smoking group.TheLeukoplakic lesions were changeable rather than static

and were most ob-vious in those on the buccal sites.