This study examines the betel nut chewing practices, and the resulting oral clinical and histological features of 20 chewers who were without the diagnostic characteristics of submucous fibrosis. All chewed pan; the average duration of the habit was 10.5 years and the average frequency 7.1 quids per day. Eleven complained of intermittent burning and soreness of the mouth and 12 depicted blanching of the mucosa. Only 2 subjects were free from symptoms or signs. Eighteen chewers revealed an abnormal epithelium with extensive hyperplasia in 10 subjects and the rest demonstrated varying degrees of hyperplasia with abnormal maturation of the epithelium. Seven of the latter showed atypia as well. Parakeratosis was present in 7 and pigment incontinence in 9. Varying degrees of chronic inflammation featured in 17 specimens and the lamina propria was dense and hyalinized in 9. No correlation was found between the histological features, the clinical features and the various aspects of the habit. It is concluded that chewing betel nut will lead to pathological changes in the mucosa, but that neither the frequency nor the duration of the habit are accurate predictors of the extent of these changes or when they are likely to occur.