Aim: Previous studies of patients (pts) with idiopathic dilated cardiomyopathy (IDCMP) were largely based on clinical diagnosis. The aim of this study was to compare the clinical and laboratory differences between pts with IDCMP and ischemic dilated cardiomyopathy (iDCMP) who underwent coronary angiography (CAG). Methods: We retrospectively evaluated 3520 subjects who underwent CAG at St. Mary���s hospital between May 2005 and May 2008. We defined echocardiographic diagnosis of DCMP as EF<40%, LV end diastolic dimension (LVEDd)>60mm. IDCMP group (34pts,M:F=24:10) had stenosis<30% on CAG and no known reversible factors such as valvular heart disease, excess alcohol drinking, peripartum CMP or drugs. iDCMP group (63pts,M:F=48:15) had stenosis>70% on CAG. Follow up duration was 470짹387 days. Results: In pts with IDCMP compared with iDCMP, age was younger (58짹12 vs 65짹12,p=0.005), EF was lower (27.0짹6.7 vs 31.7짹5.8%,p=0.001), LVEDd (69.6짹7.9 vs 66.0짹6.4mm, p=0.016) and LVEDs (58.8짹9.6 vs 52.6짹7.6mm, p=0.001) were larger, Hb (13.6짹2.4 vs 12.4짹2.4g/dL,p=0.025) and Hct (40.2짹7.0 vs 37.0짹6.9%,p=0.03) were higher. In IDCMP pts, admission due to heart failure was more frequent (p=0.0001), but survival was better than iDCMP (p=0.003) (Fig). HDL level was the factor predicting long-term survival (p=0.032, CI 1.01-1.36, OR 1.17). Conclusion: IDCMP has quite different clinical and laboratory characteristics from iDCMP. Especially, angiographically proven coronary artery disease must be one of the most important factors affecting long-term survival.