Although the roles of smoking and drinking alcohol in the aetiology of oral cancer are common knowledge among the medical community, those who have the disease are often less well informed. To quantify this potential lack of knowledge, 152 patients being reviewed after treatment for oral cancer were questioned about their smoking habits, alcohol consumption, and their understanding of the part these factors play in the development of malignancy. At least six months after the diagnosis of their malignancy, 72 (47%) still smoked and 55 (36%) drank alcohol to excess. Only one-third were aware that these habits were important in the development of oral cancer. These results indicate widespread ignorance and suggest that education about the causes of oral cancer is required in the population as a whole and particularly among those with the disease.