Clopidogrel is an antiplatelet drug with high intraindividual variability in systemic exposure and efficacy. It has been used for treating atherosclerosis and acute coronary syndrome and in preventing stent restenosis and thrombotic complications after stent implantation in clinical practice for nearly 20 years. In this study we aimed to evaluate the bioequivalence of 2 clopidogrel hydrogen sulfate formulations (75-mg tablets) under fed (n = 66) and fasted (n = 66) conditions by using the reference-scaled average bioequivalence method. An open-label, randomized, 3-sequence and 3-period crossover (3x3), semireplicated study was designed and conducted. Clopidogrel concentration of plasma samples was measured by high-precision liquid chromatography and tandem mass spectrometry. The pharmacokinetic parameters were derived by a noncompartmental model. In the fed condition the geometric least-squares mean ratios of peak concentration (C-max) and area under the concentration-time curve (AUC(0-t)) were, respectively, 103.38% and 98.97%, and the corresponding 90%CIs were 95.68% to 111.70% and 94.67% to 103.47%. In the fasted condition the geometric least squares mean ratios of C-max and AUC(0-t) were, respectively, 106.53% and 105.77%, and the corresponding 90%CIs were 97.62% to 116.25% and 96.96% to 115.38%. According to the criteria for bioequivalence (80.00% to 125.00%), the test formulations of clopidogrel and Plavix were determined to be bioequivalent.