An increased risk of cancer of the upper aerodigestive tract has been demonstrated among the members of the Danish Brewery Workers Union. To determine the role of tobacco, beer and strong liquors in the development of these cancers, a case-control study was conducted among those brewery workers who during the years 1943-1972 developed cancer of the pharynx (excluding nasopharynx), larynx, or esophagus. Controls were chosen among brewery workers who did not develop these cancers. Data concerning individual drinking and smoking habits were collected retrospectively from hospital records and by means of a mailed, self-administered questionnaire for patients or their relatives. An analysis based on the combined set of information from the two sources, showed an increased relative risk of developing an upper aerodigestive cancer, with increasing daily tobacco consumption. Likewise, we found an increasing relative risk with increasing daily alcohol consumption, statistically significant for oesophagus cancer and for all three cancer types as a whole. When looking at daily beer consumption alone, the same increased risk was found, but was only statistically significant for oesophagus cancer. No evidence of any particularly heavy consumption of strong alcoholic beverages was seen amongst the brewery workers as a whole or amongst the cases. Thus, the study supports the hypothesis that heavy beer intake may be a risk factor in the development of upper aerodigestive cancer.