On the Chinese mainland, betel quid (BQ) chewing is common in the Hunan and Hainan provinces. The BQ chewing habit in Hunan consists of dried husks and betel nuts, which are sold as industrially packaged, areca nut-based products. In Hainan, the fresh nut is chewed. Tobacco is not added. Reported prevalence of BQ chewing in Hunan province is high (64.5-82.7%). Oral diseases associated with BQ chewing are oral submucous fibrosis (OSF), oral leukoplakia (OL) and oral cancer. Reported prevalence of OSF among BQ chewers ranges from 0.9% to 4.7%. People most commonly affected are between the ages of 30 and 39 years, and 40 and 49 years. The reported prevalence of OL in Hainan ranges from 2.1% to 2.5%. In BQ chewers who also smoke, the reported prevalence is 20.3%. The prevalence of OL in Hunan province ranges from 0.1% to 0.5%. The prevalence of oral cancer among BQ chewers is low, ranging from 0.02% to 0.05%. In cases of OSF, reported prevalence is 2.6% and 1.2%. Presently, data on prevalence of BQ chewing in southern provinces of Mainland China is limited. BQ chewing habits, however, seem to differ between geographic areas. Future case-control studies are necessary to evaluate the risk for oral cancer and other associated oral mucosal diseases resulting from variations in BQ chewing habits.