A B S T R A C TBackground: Dietary saturated fat and cholesterol are the cause of atherosclerosis and cardiovascular disease. Objectives: This study aimed to assess diet quality after diagnosis of Coronary Heart Disease (CHD). Patients and Methods: This descriptive study was performed on 242 patients with diagnosis of acute coronary syndrome admitted to a coronary care unit in a cardiology clinic between December 2005 and December 2006. The study questionnaire, including questions about personal information such as age, sex, and education level, was completed by face-to-face interview. Additionally, Diet Quality Index (DQI) was used to assess the subjects' nutritonal status. Then, one-way ANOVA and chi-square tests were used where appropriated to compare the study groups. Besides, linear regression models were used to assess the associations between DQI score and the patients' sociodemographic characteristics and lifestyle factors. P value ≤ 0.05 was considered to be statistically significant. Results: The patients' ages ranged from 26 to 85 years and 68.5% of the patients were male. Considering DQI scoring, 22.7%, 75.2%, and 2.1% of the patients got "inadequate/ low", "average", and "acceptable/high" DQI, respectively. In addition, 28% of the patients consumed 40% of calories from total fat, while 55% consumed 30 -40% of calories from total fat. Also, nearly 30% of the patients consumed greater than 13% of calories from saturated fat, while 64% consumed 10 -13% of calories from saturated fat. Conclusions: In this study, most of the CHD patients got low DQI scores. In general, CHD can be prevented. However, if precautions regarding lifestyle modification are not followed, CHD is expected to progress.