Increased QT dispersion (QTd), predicting patients with risk of malignant arrhythmia, have recently been reported in hemodialysis patients (HDp). In this prospective study, we aimed to investigate changes in QTd and signal averaged-ECG (SAECG) in HDp after transplantation. Twenty-seven HDp (M/F:18/9, mean age 30+/-8 years) and 24 controls (M/F:14/10, mean age 33+/-6 years) were included. All QT parameters (QTmax, Qtmin, and QTd) were increased in HDp. QTmax and QTd started to decrease at the first month after transplantation. Percentage change in QTd at the third month was significantly correlated with percentage change in LV mass index (r=0.45, P=0.04), serum calcium (r=-0.47, P=0.02) and intact parathyroid hormone (r=0.68, P=0.01). In multivariate regression analysis, only percent chance in LV mass index was retained as significant. As for analysis of SAECG, 4 of the 23 (17%) HDp has abnormal late potentials which disappeared after transplantation. HDp with LV hypertrophy had higher filtered-QRS duration compared to patients without hypertrophy (110+/-12 vs. 97+/-11 msec, P=0.01). It was concluded that increased QTd and presence of late potentials improved early after renal transplantation. These changes were mainly associated with the regression of the LV mass.