The modified Glasgow Prognostic Score (mGPS) is one type of inflammation-based index; it includes data on elevated C-reactive protein and reduced albumin content. The predictive value of mGPS for outcomes is investigated in various diseases such as cancer, heart failure, myocardial infarction, acute pulmonary embolism, and inflammatory bowel diseases. This study aimed to evaluate the link between mGPS and the severity and complexity of peripheral arterial disease (PAD) as determined by the Transatlantic Intercommunal Consensus Document (TASC-II) classification and the prediction value of mGPS for procedural success in patients undergoing endovascular treatment (EVT). Our study included 203 consecutive patients receiving EVT for atherosclerotic obstruction of aortoiliac, femoro-popliteal, and below-knee arteries between January 2019 and February 2020. The lesion characteristics were determined according to categories in the TASC-II. Operational failure is the inability to position the guidewire through the occluded lesion following percutaneous intervention or achieve distal perfusion following EVT. In our study, we observed 136 patients (%6) with TASC A-B lesions and 67 patients (%33) with TASC C-D lesions. EVT was performed on the femoro-popliteal artery in 59.4% of the patients, on the aortoiliac artery in 30.7%, and on the below-the-knee artery in 9.9%. mGPS was an independent predictor of severe PAD (OR: 17.943, 95% CI: 5.120-62.882; p < .001) and procedural success (odds ratio: 0.004; 95% CI: 0.001-0.099; p < .001). Additionally, we identified age and the presence of a TASC D lesion as independent predictors of interventional success (OR: 0.938, 95% CI: 0.819-0.979; p: .034; OR: 0.104, 95% CI: 0.107-0.643; p: .015, respectively). We determined that mGPS independently predicts PAD complexity and severity based on TASC-II classification; the EVT success rate is lower in patients with high mGPS.