Objective: Peripheral arterial disease (PAH) is a chronic, progressive disease characterized by arterial stenosis or occlusion. Atherosclerosis is the most common cause of PAH (>90%). Carbamylation is one of the post-translational modification mechanisms of proteins and has been identified as a new risk factor for atherosclerosis. The most common carbamylation product known is homocitrulline. Our aim in this study was to contribute to the elucidation of the role of homocitrulline in the diagnosis of PAH. Methods: 70 patients with PAH and 65 individuals without PAH were included in the study. Serum homocitrulline and lysine levels were measured by AB Sciex API 3200 (Applied Biosystems/MDS Sciex) liquid chromatography-tandem mass spectrometry (LC-MS/ MS) device. Various hematological and biochemical parameters of the patients were measured in Beckman Coulter LH 780 and Beckman Coulter AU 5800 (Beckman Coulter, Brea, USA) autoanalyzers, and C-reactive protein (CRP) levels were measured in IMMAGE 800 (Beckman Coulter, Brea, USA) device, respectively. Results: Serum homocitrulline concentrations of patients with PAH were statistically significantly higher than the control group (p<0.001). Receiver Operating Characteristic (ROC) analysis showed that the optimal serum homocitrulline cut-off value was 165.1 µmol / mol lysine (p<0.001) (sensitivity, 71.4% and specificity, 86.7%) for PAH. The area under curve (AUC) value was 0.873 (95% confidence interval: 0.8040.925). There was a positive correlation between serum homocitrulline and urea, CRP, the neutrophillymphocyte ratio (NLR) and the platelet-lymphocyte ratio (PLR) levels. Conclusion: Our findings show that homocitrulline levels are significantly elevated in patients with PAH, and homocitrulline may be a useful marker in the early diagnosis of PAH.