ABSTRACT Background Mutations in the human telomerase reverse transcriptase (TERT) promoter contribute to increased TERT activity. The purpose of the present study was to assess the prevalence of TERT promoter mutations in oral cavity squamous cell carcinoma (SCC). Methods Total DNA was extracted from 201 oral cavity SCC tumors and adjacent normal tissues. Primers were used to amplify the sequence region containing 2 TERT promoter mutations (C228T and C250T) that were then sequenced using the Sanger method. Results Sequencing revealed that 52.5% (104/201) and 12.9% (26/201) of oral cavity SCC tumor tissues and 6.0% (12/201) and 2.5% (5/201) of adjacent normal tissues contained C228T and C250T mutations, respectively. In addition, the C228T mutation was significantly associated with betel nut chewing. Conclusion Our results show that mutations in the TERT promoter occur in patients with oral cavity SCC at a high frequency. This suggests that somatic TERT promoter mutations could play a vital role in the pathogenesis and progression of oral cavity SCC. © 2017 Wiley Periodicals, Inc. Head Neck 39: 1131–1137, 2017