OBJECTIVE To characterize the sonographic features of the buccal mucosa in patients with oral submucous fibrosis (OSF). METHODS Three groups (controls with areca-related habits, controls without areca-related habits and clinically diagnosed OSF cases), each comprising 30 subjects, were included in the study. After a thorough clinical examination, transcutaneous B-mode ultrasonography was performed with a multifrequency linear transducer (5-10 MHz) for anterior and posterior buccal mucosa bilaterally. Both clinical and ultrasound findings were recorded by three independent observers. One-way analysis of variance and Tukey's honestly significant difference post-hoc tests were used for statistical comparisons between groups and Pearson χ(2) tests to compare the proportions. Kappa statistics was used to determine the interobserver agreement. RESULTS The submucosa that appeared hypoechoic in the control groups had significantly increased echogenicity in the case group (hypo- to isoechoic in 46.7% and isoechoic in 53.3%). The differentiation between the submucosa and the muscle layer appeared distinct in the control groups while it was not clear in the case group (indistinct in 50% and completely lost in 50%). The number of sites found positive on the ultrasound was significantly greater than the number of clinically positive sites. There was a very good interobserver consistency in clinical and ultrasound findings. CONCLUSIONS Ultrasonography of the buccal mucosa demonstrates increased submucosal echogenicity and reduced echo differentiation between submucosa and muscle layer in OSF cases. Hence, it can be used as a non-invasive imaging modality to assess the disease extent and severity across the entire buccal mucosa to supplement clinical evaluation.