Abstract： Objective To investigate the prevalence of betel nut chewing and oral submucous fibrosis(OSF)among elementary and middle school students in Loudi city,Hunan province.Methods According to the standard of the third national oral health epidemiological investigation,the subjects were selected through a two-stage random sampling procedure.A face to face questionnaire survey was conducted among students by random sampling from 6 schools,and oral examination was performed to find the prevalence of OSF.Results Of the 4087 eligible students,4019 students participated in the survey (98.3%).Among the 4019 students,there were 498 betel nut chewers,the prevalence of betel nut chewing was 12.4%.which was much higher in male than in female students(437/2073,21.1% vs 61/1946,3.1%,P＜0.05).The proportion of students who were chewing areca nuts increased with increasing grades (P＜0.05).The prevalence was highest in senior schools(229/1077,21.3%)and lowest in elementary schools(126/1983,6.4%).Most students who were chewing areca nuts in elementary school obtained betel nuts from their parents(61/126,48.4%),but most middle sehool betel nut chewers obtained betel nuts from their friends(88/143,61.5%and 165/229,72.1%).Five OSF cases(0.12%)were diagnosed among the 4019 students,all of them were male senior school students.Conclusions Betel nut chewing was common and OSF cases were found among elementary and middle school students in Loudi city.There were more male than female students who were chewing betel nut.