Several studies have indicated a lack of nutritional knowledge among physicians. As there is no published data in nutritional knowledge among physicians in Saudi Arabia, hence the purpose of this current study was to assess the nutrition knowledge of primary care physicians working in Riyadh, Saudi Arabia. Nutrition knowledge questionnaire consisted of 16 multiple-choice questions, was mailed to 105 primary care physicians working in Riyadh, Saudi Arabia. The questionnaire was pre- tested in a pilot study. Non-respondents received a second questionnaire and a phone call. Of the 105 primary care physicians, 59 replies were received (56.2%). The mean mark for correctly answered questions was 51.7%. Approximately 75 % of the physicians described their knowledge of nutrition as `Poor`. The results indicate that physicians are generally aware of information which has been publicized in the medical press: nutrient which helps prevent thrombosis (omega-3 fat); the preventive action of fruit and vegetables against cancer; which nutrients are antioxidants; the nutrient associated with the prevention of neural tube defects (folate). By contrast they have a poor knowledge of other important topics in nutrition: the major type of fat in olive oil; hydrogenated fats; source of vitamin B12; Substance raises the blood HDL-cholesterol level (Alcohol); the association between excess protein intake and calcium loss; the type of dietary fiber helpful in lowering the blood cholesterol level (soluble fiber) and Nutrient is protective against hypertension. These results support other data that physicians need more education in nutrition. Nutrition should be an essential part in continuing medical education.