The most common form of oral surgery is extraction of impacted third molars. The patient may suffer a period of impaired food intake before extraction because of the discomfort caused by the impacted tooth. This may compound poor intake for other reasons, for example poverty. After surgery, the patient undergoes several days of pain and swelling, which delays a return to normal eating. The relationship between surgery for impacted third molars and diet has not been documented, nor is dietary advice routinely offered. The aim of this study was to describe the diet of patients before and after extraction of third molars. Patients recorded everything they ate for 7 days before and after surgery. These records were converted into estimates of nutrient intake. A substantial fall in energy intake occurred which had not been corrected even a week after surgery. The nutritional implications of this are not yet clear. Practitioners are strongly advised to warn patients of the likelihood of serious disturbance to their lifestyle and to offer them simple dietary advice.