INTRODUCTION High posttreatment platelet reactivity to clopidogrel (HPPR) is associated with major adverse cardiac events. However, the clinical predictors of HPPR in Asians have not been studied previously. AIMS We sought to determine clinical predictors of HPPR in Koreans. RESULTS We measured platelet reactivity with the VerifyNow P2Y12 assay in 1431 consecutive patients undergoing coronary angiography. We used the cut-off value of greater than 275 P2Y12 Reaction Unit (PRU) to define patients with HPPR. The clinical characteristics were compared between patients with HPPR (36.3%) and those without HPPR (63.7%). The mean age (65.4 ± 9.1 vs. 62.2 ± 9.7 years) was higher, hypertension (68.5% vs. 62.0%), diabetes mellitus (35.4% vs. 28.5%), chronic kidney disease (36.3% vs. 22.5%), renal replacement treatment (1.2% vs. 0.2%), and congestive heart failure (1.3% vs. 0.3%) were more common among patients with HPPR, while male gender (72.6% vs. 54.8%) and smoking (19.9% vs. 13.1%) were more common among non-HPPR patients. Mean glomerular filtration rate (63.5 ± 18.6 vs. 69.7 ± 16.1 mL/min/1.73 m(3) ) was lower and C-reactive protein (hs-CRP) (6.6 ± 20.5 mg/L vs. 4.2 ± 12.1 mg/L) level was higher among those with HPPR. Independent predictors of HPPR were female gender (OR 1.90, P≤ 0.001), chronic kidney disease (OR 1.51, 0 = 0.004), diabetes mellitus (OR 1.35, P= 0.024), hs-CRP ≥ 2.0 mg/L (OR 1.31, P= 0.005), and age increase in decades (OR 1.21, P= 0.002), while smoking was negative risk factor (OR 0.63, P= 0.015). The number of risk factors was linearly associated with the risk of HPPR, with most patients having one or two predictors. CONCLUSION In Korean population, independent clinical predictors of HPPR included diabetes mellitus, increased age, female gender, chronic kidney disease, and hs-CRP ≥ 2.0 mg/L, while cigarette smoking was associated with better responsiveness. Mean platelet reactivity and HPPR prevalence steadily increased with the number of clinical predictors.