A case-control study of 374 patients with primary epithelial cancers of the oral cavity, oro- and hypopharynx, and larynx is reported, the controls being patients with selected other cancers, matched for age and sex. Of all eligible patients, 93 % were interviewed. Increased risks were seen with alcohol consumption and, less strongly, with smoking, which for all sites could be adequately fitted by either a multiplicative or an additive model. However, the site-specific relationships were different, alcohol consumption being significantly associated only with oral cavity, pharyngeal and extrinsic laryngeal tumours, and smoking only with intrinsic laryngeal tumours. Increased risks were associated with low socio-economic status, the unmarried state, and poor dental care. No significant associations were seen with specific occupational exposures.