OBJECTIVES: We aimed to determine primarily the oral health status of patients with upper aerodigestive tract cancer before radiotherapy, and secondarily the prevalence of risk factors for poor oral status. METHODS: A cross-sectional study was conducted in Marseille University hospital. Assessment criteria were the Decay, Missing and Filled (DMF) Index and periodontal status. RESULTS: One hundred and fifty-four patients, mean age 60.9years, were included. The most common sites of primary tumors were the larynx (28.6%) and oral cavity (26.6%). Current or past smokers accounted for 80.5% of patients and 67% were alcohol abusers. Most patients (83.8%) did not have xerostomia. They ate three meals a day (61%), with sugar consumption in 40%. The median number of daily tooth brushings was 2, with a manual toothbrush (81.2%). Few patients used dental floss or interproximal brushes. Individual DMF index was 17.6 (D=2.3, M=9.3, F=6.0) and was higher in patients with xerostomia and alcohol abusers (P=0.01). Osseous level was 62.3% and 57.8% of patients had osseous infections, which were more common with poor hygiene (P=0.04). Most patients (85.7%) had periodontal disease, but incidence did not significantly differ according to risk factors. DISCUSSION: The DMF index was higher in presence of periodontal disease and osseous infections. Alcohol and xerostomia were associated with a high individual DMF index and osseous infections were more frequent in patients with poor hygiene. Patients with upper aerodigestive tract cancer are at high risk of osteoradionecrosis if they do not receive dental treatment before radiotherapy. Copyright © 2017 Elsevier Masson SAS. All rights reserved.