Introduction VerifyNow P2Y12 is commonly used to measure responsiveness to clopidogrel. We sought to compare the results obtained from novel INNOVANCE (R) PFA P2Y and VerifyNow P2Y12 assay to assess the clopidogrel resistance in patients undergoing percutaneous coronary intervention. Methods A total of 255 patients undergoing percutaneous coronary intervention, preliminarily treated with 100 mg/day of aspirin followed by coadministration of clopidogrel (loading dose, 600 mg; maintenance dose, 75 mg/day), were enrolled in this study. Platelet aggregation was measured by INNOVANCE (R) PFA P2Y and VerifyNow P2Y12. Results INNOVANCE (R) PFA P2Y and VerifyNow P2Y12 assay showed moderate correlations with INNOVANCE (R) PFA P2Y vs. VerifyNow%inhibition: r similar to=similar to 0.412, P similar to<similar to 0.0001; INNOVANCE (R) PFA P2Yvs.VerifyNow P2Y12 reaction units (PRU): r similar to=similar to-0.402, P similar to<similar to 0.0001. The agreement between INNOVANCE (R) PFA P2Y and VerifyNow%inhibition was 85% and that of INNOVANCE (R) PFA P2Y and VerifyNow PRU was 79%. The k statistics between INNOVANCE (R) PFA P2Y and VerifyNow%inhibition and PRU were 0.52 and 0.44, respectively. Conclusions The sensitivity of INNOVANCE (R) PFA P2Y in detecting clopidogrel resistance is comparable to that of VerifyNow P2Y12 assay. As the PFA-100 (R) system is already widely used, the new test cartilage may be a useful tool for the assessment of clopidogrel effects. Additional clinical correlation studies are required to validate the effectiveness of INNOVANCE (R) PFA P2Y in predicting long-term clinical outcomes. J. Clin. Lab. Anal. 26:262-266, 2012. (c) 2012 Wiley Periodicals, Inc.