Objective To investigate the change of QT dispersion (QTd) in 60 patients with uremia undergoing maintenance hemodialysis (MHD), the relationship between QTd and ventricular arrhythmia in MHD patients, and the factors relating to QTd. Methods 12-lead ECG was conducted in 60 MHD patients before and after dialysis, and their QTds were calculated. Clinical observation, laboratory examinations and statistical analysis were performed. Results Before hemodialysis, QTd values were higher in patients with ventricular arrhythmias than those without ventricular arrhythmias (P＜0.01). QTd values became higher after hemodialysis (P＜0.01). Regression analysis showed that the magnitude of QTd increase positively correlated with the magnitude of K+ and HCO3- concentration changes (r=0.67, P＜0.01, and r=0.79, P＜0.01, respectively) after hemodialysis. Conclusion QTd value may relate to the presence of ventricular arrhythmias in MHD patients. QTd increases further after hemodialysis, probably resulting from the rapid change of serum K+ concentration and rapid correction of acidosis.