Objectives: Diet diaries are recommended as a tool to support behaviour change in dental patients at high risk of dental diseases. However, little is known about their use in dental practice. This study aimed to investigate whether and how general dental practitioners (GDPs) use diet diaries and identify factors which influence their use. Methods: A postal questionnaire was sent to a stratified random sample of general dental practitioners. The questionnaire asked about demographic and professional characteristics of the GDPs and their practices regarding diet advice, collection of dietary information, diet diaries usage (e.g. frequency, considerations and barriers), and interpretation of diet diaries. Descriptive, bivariate and multivariate analyses were conducted. Results: From 972 eligible GDP participants, 250 (26%) responses were received. Whilst almost all of these GDPs reported giving diet advice to patients routinely, and 40% reported also referring to dental care professionals in the practice to deliver dietary advice, only 28% (70) reported that they are involved in using diet diaries. GDPs appeared to target patients for dietary advice: GDPs reported they personally gave diet advice to an estimated 63% of their patients, and referred patients to DCPs for diet advice for 11% of their (GDPs’) patients. GDPs used diet diaries more often for child than adult patients. Diet diaries usage was lower among younger dentists and in practices with higher percentages of NHS patients (p<0.05). Perceived insufficient remuneration for time involved in using diet diaries was the main reason given for their lack of use. Conclusion: Although recommended as best practice, most English GDPs do not frequently use diet diaries to collect diet information in dental practice, mainly due to perceived financial and time constraints. Development of a more efficient tool to assess the dietary habits of dental patients is needed. Key words: diet, dental practice, health education, caries, diary, England