Apelin is a bioactive peptide. Apelin and its receptor APJ are widely distributed in different cell tissues, and involved in a wide range of functions in the cardiovascular system. In this study we investigated whether plasma apelin and some other parameters of coronary artery diseases (lipid profile, creatinine kinase "CK-MB", lactate dehydrogenase "LDH", Troponin T "Tn-T", and High Sensitivity C-reactive protein "hs-CRP") levels were altered in plasma of normal and atherosclerotic subjects. We also assessed the association between plasma apelin and other body parameters in these subjects. Methods: The study included 60 patients with coronary artery disease. Patients compared with 24 healthy subjects as control group. The apelin and Tn-T were estimated by competitive ELISA test using commercially available kit. lipid profile, CK-MB, LDH, and hs-CRP were estimated by colorimetric method. Lipid profiles were determined by using available commercial kits. Results: Plasma levels of apelin in patients were significantly lower (p<0.05) than controls. While, CK-MB, LDH, Tn-T and hs-CRP show significant elevation (P<0.05) in patients compared to control group. Plasma levels of total Cholesterol (TC), low density lipoprotein (LDL), very low density lipoprotein (VLDL), and Triglyceride (TG) were significantly higher (p<0.05) in patients as compared to control group. However, high density lipoprotein (HDL) in patients shows significant decreasing (P<0.05) in comparison to control. Apelin shows no significant correlation with other body parameters in these patients. Conclusion: In this study obtained apelin levels were found to be significantly lower in patients as compared to control group, but not correlated with other studied parameters in patients. Decreasing apelin may be one of the causes for development of vascular disease, or decreasing apelin may be another factor increasing atherosclerotic process, and can be used for diagnosing Atherosclerosis.