OBJECTIVE: To study the ECG features in children with dilated cardiomyopathy (DCM), and related factors for the occurrence of arrhythmia secondary to DCM. METHODS: Data from 68 children with DCM from January 1998 to March 2010 were studied. The children were classified into three groups: severe arrhythmia (n=42), non-severe arrhythmia (n=20) and non-arrhythmia (n=6). Left ventricular end diastolic diameter (LVED), left ventricular ejection fraction (LVEF) and left ventricular fractional shortening (LVFS) were compared. RESULTS: Abnormal ECG results were found in all of the 68 children with DCM. Sinus tachycardia (91%) and ectopic pulsatile (86%) were common. LVED in the severe arrhythmia group (74±6 mm) was greater than that in the non-severe arrhythmia group (65±4 mm; P<0.05) and non-arrhythmia group (61±3 mm; P<0.05). LVED in the non-severe arrhythmia group was also greater than that in the non-arrhythmia group (P<0.05). LVEF and LVFS in the severe arrhythmia group were (30±11)% and (22±4)%, respectively, which were lower than those in the non-severe arrhythmia group［(37±12)% and (28±5)%, respectively］and non-arrhythmia group［(45±9)% and (34±7)%, respectively］(P<0.05). There were also significant differences in the LVEF and LVFS between the non-severe arrhythmia and non-arrhythmia groups (P<0.05). CONCLUSIONS: The common abnormal ECG findings are sinus tachycardia and ectopic pulsatile in children with DCM. Arrhythmia is one of the main clinical manifestations of DCM. The occurrence of arrhythmia is associated with the left ventricular size and heart function.