Background:Dyslipidemia is an established risk factor for coronary artery disease (CAD). Despite this, only half of CAD patients present with fasting dyslipidemia. Some reports have linked postprandial lipemia to atherosclerosis.We aimed to test the relationship between postprandial lipid profile (after fat loading) and CAD severity assessed by the SYNTAX score.Methods:We included 53 patients with documented CADs. We checked both fasting and postprandial (2 hours) lipograms after fat loading with 17 g/body surface area (m2). Then we assessed CAD severity via coronary angiography using the SYNTAX score. Our study is registered in clinicaltrials.gov (NCT03175393).Results: We observed a significant increase in postprandial triglycerides (TGs); TGs (154.30 ±73.23 vs. 128.07 ± 69.40 mg/dl; P < 0.001), very-low-density lipoproteins (VLDL) (30.85 ± 14.65 vs. 25.60 ± 13.93 mg/dl; P < 0.001) as well as a significant decrease in the postprandial level of total cholesterol (162.37 ± 45.86 vs. 168.26 ± 45.96 mg/dl; P = 0.03) in comparison to their fasting level.We found that the SYNTAX score had a significant positive moderate correlation with 2-hour postprandial TGs (r = 0.55; P < 0.001) and 2-hour postprandial VLDL (r = 0.50; P < 0.001).Predictors of high SYNTAX scores were the male gender (odds ratio: 6.362, confidence interval: 0.78–11.94, p = 0.028), postprandial low-density lipoproteins (odds ratio: 0.280, confidence interval: 0.004–0.135, p = 0.039), and postprandial high-density lipoproteins (odds ratio: 0.325, confidence interval: 0.12–1.012, p = 0.017) with an adjusted R2 of 0.51.Conclusion: Postprandial lipograms, especially TGs, are significantly and positively related to CAD severity.