Background: Due to the controversy over the effect of serum testosterone levels on coronary artery diseases, this survey explores the serum levels of free testosterone, luteinizing hormone, and follicle-stimulating hormone in candidates for coronary artery bypass graft compared with an age-matched control group and evaluates the associated factors in these participants. Objective: To determine the testosterone level in elective coronary artery bypass grafting participants. Materials and Methods: In this cross-sectional study, all male patients aged > 40 yr as candidates for elective coronary artery bypass grafting, who were referred to the Afshar Hospital, Yazd, Iran, from March 2018 to March 2019, were included. In total, 100 men were enrolled (50 cases and 50 controls). Their serum levels of free and total testosterone, luteinizing hormone, and follicle-stimulating hormone were measured and the results were compared. Results: The findings indicated a significant difference between the two groups in total and free testosterone (both p < 0.001); they were lower in the case group. There was also a significant difference in the total testosterone of the participants with diabetes mellitus compared with no-diabetic individuals (p = 0.007). Free testosterone of diabetic subjects taking insulin was lower compared with those taking no insulin (p = 0.04). There was also an association between the body mass index and free testosterone, left ventricular ejection fraction and total testosterone, and a significant and negative relation between the duration of hospital admissions and free testosterone (p < 0.05). Conclusion: This study illustrates that participants with coronary artery disease bear a significantly low testosterone level in comparison with the healthy control group. Key words: Coronary artery disease, Testosterone, Coronary artery bypass graft surgery.