Background: Coronary artery diseases are among the most prevalent causes of mortality worldwide. Multiple investigations indicate that coronary artery disease is related to insulin resistance in both diabetic and non-diabetic cases. The aim of the study is to assess the relationship between insulin resistance (IR) and coronary artery disease incidence and the severity of lesions. Methods: A cross-sectional investigation included 100 cases admitted with acute coronary syndrome to coronary care unit then Coronary angiography was done at cardiology department in 2022. blood samples were taken, and laboratory tests levels were done done. The homeostatic model assessment index of IR (HOMA-IR) has been utilized for determining IR. The HOMA-IR has been determined utilizing the following formula: Baseline serum insulin concentration (milliunit per liter) x Baseline plasma glucose (milligrams per deciliters)/405. The TYG index has been estimated utilizing the following formula: Ln (Fasting triglycerides (milligrams per deciliters) x Fasting blood glucose (mg per deciliters)/2). Finally, coronary angiography has been performed. Results: 83% of study group show high level of HOMA-IR level however only 34% of cases where diabetics all cases show high level of TyG index which is another index for insulin resistance. mean fasting insulin was (22.5±22.6). The mean level of HOMA-IR was (12.6±20.1) and the mean level of TyG index was (10±50.2) Conclusions: The study showed a significant correlation betweeen coronary heart disease incidence and resistance of insulin in diabetic and non-diabetic cases.