Background: Patients with schizophrenia (SCZ) have a higher risk of cardiovascular diseases and acute myocardial infarction than the average population. Early diagnosis of SCZ patients with subclinical atherosclerosis is great importance in reducing cardiovascular morbidity and mortality. Carotid intima-media thickness (CIMT) is a well-studied marker of early atherosclerosis. Methods: Fifty-one SCZ patients (20 females, 31 males) and 55 healthy controls (HCs) (25 females, 30 males) were included in the study. Electrocardiography (ECG), lipid parameters, hemogram, and biochemistry values of the participants were taken. Low-density lipoprotein (LDL), high-density lipoprotein (HDL), fasting triglycerides, and total cholesterol were measured. The arrhythmogenic index of plasma (AIP) was analyzed. Results: The mean age was 36.64±7.81 years in the SCZ group and 38.50±7.29 years in the HCs group. QT interval (p=0.035), CIMT-left (p=0.008), CIMT-right (p=0.002), fasting triglyceride (p=0.005), AIP (p=0.005) in the SCZ group compared to HCs (<0.001) was statistically higher, while HDL (p=0.003) was statistically lower. According to Pearson correlation analysis, CIMT-left was positively correlated with age and QT interval (r=0.568, p<0.001 and r= 0.589, p<0.001, respectively). CIMT-right value was also positively correlated with age and QT interval (r=0.533, p<0.001 and r= 0.555, p<0.001, respectively). QT interval positively and significantly predicted CIMT-left and CIMT-right (p<0.001, β=0.549 and p=0.001 and β=0.506 accordingly). Conclusion: Considering that antipsychotic treatments can cause dyslipidemia, hyperglycemia, and being overweight, efforts should be made to detect and correct these additional cardiovascular risk factors early in SCZ patients.