Poor oral hygiene is believed to play a role as a risk factor for head and neck cancer, especially for oral cancer. Only few epidemiologic data exist about dental status and oral hygiene in these patients. We performed a case-control study involving 100 patients with squamous cell carcinoma of the upper aerodigestive tract and 214 age- and sex-matched control subjects with no known tumorous disease. In the tumor patients, oral hygiene and dental status proved to be significantly worse: the majority of the tumor patients seldom or never brushed their teeth and the frequency of dental visits was significantly lower. Tartar of 3 mm or more was found in 40.9% of the tumor patients and in 22% of the control subjects. In the tumor group, the incidence of decayed teeth was significantly higher compared with the control subjects. Chronic inflammation of the gingiva was observed in 28% of the tumor patients vs. 13.5% in the control group. Oral hygiene was negatively correlated with alcohol as well as with tobacco consumption. The social status of subjects also correlated with oral hygiene, which was found to be worst in subjects from the lower social strata. The present study revealed a poor dental status and oral hygiene in patients with head and neck cancer. The pathogenetic mechanism being associated with this suspected risk factor remains to be investigated.