Predicting sudden cardiac death (SCD) in patients with dilated cardiomyopathy (DCM) is difficult, so the present study evaluated the efficacy of microvolt-level T-wave alternans (TWA) and compared it with conventional parameters for prospective risk stratification of SCD in patients with DCM. Eighty-two patients with DCM (53±15 years old, 67 M/15 F) underwent assessment of TWA, left ventricular end-diastolic diameter (LVDd), left ventricular ejection fraction (LVEF), signal-averaged ECG, and analysis of 24-h Holter monitoring and QT dispersion (QTd). The endpoint of the study was defined as either SCD or documented sustained ventricular tachycardia/ventricular fibrillation (SVT/VF) during the follow-up period. During an average follow-up period of 24 months, 1 patient died suddenly and 9 patients had SVT/VF. Kaplan-Meier survival analysis showed that TWA, LVEF (≤35%), nonsustained ventricular tachycardia, and QTd (>90 ms) were significant univariate risk stratifiers (p<0.005, p<0.005, p<0.005, and p<0.05, respectively). Multivariate Cox regression analysis showed that TWA and the LVEF were statistically significant independent risk stratifiers (p<0.05 and p<0.01, respectively). A combination of TWA and LVEF identified high risk DCM patients (p<0.01); TWA for the electrical substrate and the LVEF for the hemodynamic function. (Jpn Circ J 2001; 65: 76 - 80)