Objective: To assess awareness about oral cancer and precancer among patients attending for dental treatment at a University Dental hospital. Methods and materials: A self-administered questionnaire was used to collect information from 410 randomly selected outpatients attended the Dental Hospital (teaching), Faculty of Dental Sciences, University of Peradeniya, Sri Lanka. The questionnaire included questions to ascertain information on socio-demographic parameters, awareness of oral cancer and precancer, habits of betel chewing, smoking and alcohol consumption. Results: Ninety five percent of the respondents were aware of the possibility of occurrence of cancer in the mouth while only 44.9% (n=184) were aware about precancer. Of the 390 individuals who were aware of the existence of oral cancer, 80.7% were knowledgeable about the causal relationship between betel chewing habit and oral cancer. Forty-seven and 17 per cent were aware of links with tobacco smoking and alcohol consumption, respectively. However, out of those who had knowledge of oral cancer, 18 % (n= 69) were not knowledgeable about associations with habits. Conclusions: This survey revealed that the patients attending the hospital were well informed about oral cancer. However, awareness about precancer was relatively low. Knowledge about the causal relationships with tobacco smoking and use of alcohol was low compared to that for betel chewing.