The aim of our study was to evaluate whether corrected QT dispersion (QTc dispersion), an electrocardiographic marker, is a good predictor of the development of acute heart failure after high‐dose chemotherapy followed by autologous or allogeneic hematopoietic stem cell transplantation. We enrolled 50 consecutive patients, from age 15 to 63 years, with hematopoietic diseases scheduled to undergo autologous or allogeneic hematopoietic stem cell transplantation, and compared QTc dispersion with other markers before transplantation conditioning. In univariate logistic analysis, QTc dispersion was a significant factor for acute heart failure after hematopoietic stem cell transplantation (odds ratio, 3.7 per 10 msec; confidence interval, 1.6–8.5; P = 0.002). There were no significant differences as age, sex, systolic or diastolic echocardiographic function markers, cumulative anthracycline dose, or QTc before transplantation between patients with and without acute heart failure. After multiple adjustments for left ventricular ejection fraction, cumulative anthracycline dose, cyclophosphamide conditioning dose, QTc dispersion was a significant and independent factor for acute heart failure after hematopoietic stem cell transplantation (odds ratio, 48.0 per 10 msec; confidence interval, 1.4–1666.3; P = 0.03). This study demonstrated that QTc dispersion could be used as a powerful noninvasive predictor of the development of acute heart failure after hematopoietic stem cell transplantation. Am. J. Hematol. 76:1–7, 2004. © 2004 Wiley‐Liss, Inc.