Background/purpose: The purpose of this study was to determine the prevalence of obstructive sleep apnea (OSA) in patients with squamous cell carcinoma (SSC) of the tongue after primary surgical resection and to correlate the presence of OSA with the occurrence of obstructive apnea in this patient population. Materials and methods: This was a retrospective study of 26 Taiwanese patients, 24 males and two females, aged 37e71 years, after surgical resection of SSC of the tongue. Patients who had a follow-up after treatment of 6 months to 11 years were eligible for inclusion. During the posttreatment period, the occurrence of OSA was determined in these patients. Overnight polysomnography (PSG) was used to determine the apneaehypopnea index (AHI). Patients were considered to have OSA if the AHI value was >5. Results: Patients with an AHI value of <5 showed a mean body mass index (BMI) of 22.8 kg/m 2 , while those with an AHI value of >5 showed a mean BMI of 28.3 kg/m 2 . The BMI distribution between patients with AHI value of <5 and those with AHI values of >5 was statistically significant (P Z 0.018). Using the definition of clinically significant sleep apnea as AHI > 5, 14 of 26 patients (53.85%) had clinical OSA. The OSA and non-OSA groups showed no statistical significance in terms of age, tumor size, tongue ablation, neck dissection [method?], or wound reconstruction methods. Conclusion: Incidence of OSA in the patient population with SSC of the tongue was found to be significantly higher than that in the general population. The limitations of this study were the Journal of Dental Sciences (2012) 7, 245e249 relatively small patient sample size and no presurgical PSG record being obtained from the patients to compare the sleep quality before and after cancer therapy.