Objective Ischemia-modified albumin (IMA) is a novel marker for the detection of ischemia. The value of this biomarker has been studied in patients with coronary artery disease (CAD). However, the relationship between the severity of coronary stenosis and serum IMA levels remains unknown. Therefore, we aimed to investigate the potential role of serum IMA levels in predicting the severity of coronary atherosclerosis. Materials and methods One hundred and forty-two individuals who underwent coronary angiography for coronary artery disease complaints were included in the study. Participants were divided into three groups based on their diagnosis as control (healthy subjects), group I (subjects with lower Gensini score), and group II (subjects with higher Gensini score). Global Registry of Acute Coronary Events (GRACE) risk score and Gensini scores were calculated after coronary angiogram in the patient groups. Then, venous blood samples were collected from each participant. Serum IMA levels and the levels of routine laboratory markers were measured. Results The serum lymphocyte, neutrophil, and high-density lipid (HDL) levels were statistically insignificant between the groups. The white blood cell (WBC) count and IMA levels were significantly higher in the patient groups (p < 0.05). The GRACE and Gensini scores were significantly different in the patient groups (p < 0.05). However, there was no significant correlation between the GRACE and Gensini scores and serum IMA levels. Conclusion Although IMA levels can be a significant predictor for ischemia according to previous reports, this biomarker seems to be insufficient for determining the severity of disease in patients with CAD.