Patency of infarct-related artery (IRA) in patients with ST-segment elevation myocardial infarction (STEMI) before primary percutaneous coronary intervention (pPCI) is associated with lower mortality and better clinical outcome. However, there were little data regarding the predictors of IRA patency before pPCI in the setting of STEMI. We aimed to assess the association of platelet to lymphocyte ratio (PLR) with IRA patency in STEMI. A total of 452 patients were enrolled and categorized as occluded or patent IRA. Patency IRA was assessed by the thrombolysis in myocardial infarction (TIMI) flow grade. Blood samples were obtained on admission to calculate PLR. Of all patients, 92 (20.4%) patients revealed pre-pPCI TIMI 3 flow in IRA. The PLR was significantly higher in occluded IRA group (138.4 +/- 51.4 vs 95.4 +/- 43.5, P < .001). Glucose, troponin I, and neutrophil to lymphocyte ratio (NLR) levels were also higher in occluded IRA group (P < .05). Multivariate regression analysis demonstrated the PLR (odds ratio [OR]: 0.987; 95% confidence interval [CI]: 0.978-0.995, P = .002) and NLR (OR: 0.758; 95% CI: 0.584-0.985, P = .038) on admission as independent predictors of IRA patency. In conclusion, a higher PLR is a powerful and independent predictor of IRA patency in patients with STEMI before pPCI.