Objectives: To evaluate the effects of L-carnitine as an adjunct therapy to percutanenous coronary intervention (PCI) for non-ST elevation acute coronary syndrome (NSTEMI).Methods: Ninety-six consecutive patients with NSTEMI were randomized into treatment group (L-carnitine 5 g IV bolus followed by 10 g/day IV infusion for three days), and control group. All patients also underwent PCI within 24h from the onset of chest pain. The peak values of creatine kinase-MB and troponin-I before and after PCI were observed. Results: In the treatment group, the peak values of creatine kinase-MB were significantly lower than the control group at 12h and 24h after PCI (P<0.01). The peak values of troponin-I in the treatment group were also lower than the control group at 8h after PCI (P<0.01). Multivariate regression analysis showed that L-carnitine therapy was an independent predictor for the reduction of creatine kinase-MB (r=0.596, P<0.001) or troponin-I (r=0.633, P<0.001).Conclusion: L-carnitine adjunct therapy appears to be associated with a reduced level of cardiac markers in patients with NSTEMI. These results support a larger clinical trial to investigate the effect of L-carnitine on cardiac events following PCI.