We evaluated the relationship between admission blood glucose levels and estimated coronary flow by the thrombolysis in myocardial infarction (TIMI) frame count (TFC) method in patients with ST-segment elevation myocardial infarction (STEMI) undergoing primary percutaneous coronary intervention (pPCI). The TFC of 121 consecutive patients with STEMI were evaluated after pPCI. Patients with admission glucose levels > 198 mg/dL (11 mmol/L) were defined as hyperglycemic. Hyperglycemia was observed in 36 (29.8%) patients. The TFC was significantly higher in patients with hyperglycemia (70.75 [10-96] vs 56.87 [8-100], P = .04). No-reflow frequency was higher in the hyperglycemia group (44.4% vs 23.5%, P = .02). In multivariate linear regression analysis admission glucose was an independent predictor of high TFC (B = 0.21, P = .02). Our findings suggest that admission blood glucose is a predictor of TFC which reflects coronary blood flow.