Background: Cardiac resynchronization therapy (CRT) represents a new therapeutic modality of proven efficacy for selected patients with heart failure and ventricular dyssynchrony. The aim of this study was to assess the mid-term effects of CRT on clinical symptoms, QRS width, and echocardiographic parameters in patients with dilated cardiomyopathy (DCMP) and inter/intraventricular conduction delays. Methods: Six DCMP patients were recruited from October 2005 to October 2007. All patients ( left ventricular ejection fraction [LVEF] < 35%, QRS width >150msec and stable New York Heart Association [NYHA] class III or IV on optimal medical treatment) underwent CRT by biventricular pacing. NYHA functional class, QRS width, left ventricular end-diastolic diameter (LVEDD), left ventricular end-systolic diameter (LVESD), left atrial volume index (LAVI), and LVEF were evaluated immediately before CRT and around one year. Results: Four men and one woman and one pediatric patient were included this study. Patients were too small to assess statistical analysis. The average age of patients except one pediatric patient was 54.2짹11.1 years. One pediatric patient was 8 years of age. Median duration of follow-up period was 18 (8.5-22) months. During the follow-up period, QRS width, LVEDD, LVESD and LAVI were not changed significantly. NYHA functional class and LVEF were improved statistically significant ( P-value 0.020 and 0.028 in Wilcoxon signed rank test ). Conclusion: CRT in DCMP patients improved NYHA functional class and LVEF without the improvement of QRS width, LVEDD, LVESD, and LAVI during mid-term follow-up.