Back ground Interleukin-18 (IL-18) has been known as a pro-inflammatory cytokine which promotes systemic inflammatory responses contribute to myocardial dysfunction in acute coronary syndrome and heart failure. We prospectively studied to clarify relations of IL-18 level to the extent of myocardial dysfunction in stress induced cardiomyopathy patients with normal coronary arteries. Methods From July 2004 to June 2006, nine patients diagnosed as stress induced cardiomyopathy were enrolled. Stress induced cariomyopathy was defined as a transient extensive akinesia in the apical and mid portions of the left ventricle in echocardiogram without significant coronary artery stenosis on coronary angiogram. We checked plasma IL-18 level and echocardiogram at the 1st day, 4th day, 7th day and 14th day after the onset of chest pain and dyspnea. Results The plasma value of IL-18 at the first day was 118.1짹 53.1pg/mL, gradually decreased with time (4th day, 119.5 짹38.1pg/mL;7th day, 117.2 짹49.8pg/mL;14th day, 85.8 짹17.8pg/mL, p<0.001). The ejection fraction (EF) of left ventricle was 36.8짹 5.5% at first day gradually improved with time (4th day, 44.9 짹5.0 %; 7th day, 52.2 짹3.0%;14th day, 62.0 짹1.4%, p<0.001).It also showed inverse trend of IL-18 concentration and left ventricular EF(p=0.05). Conclusion Plasma IL-18 concentrations increased at the onset of symptom and gradually decreased with time in stress induced cardiomyopathy by contraries myocardial contractility. This results may imply the association of proinflammatory IL-18 and stress induced cardiomyopathy. Further large scale studies are required to demonstrate the role of IL-18 contribute to stress induced cardiomyopathy.