Background: Coronary collateral circulation (CCC) is linked to myocardial remodeling severity in patients with chronic ischaemic heart disease (IHD). However its effect on left ventricular reverse remodeling (LVRR) in patients with chronic IHD underwent coronary artery bypass surgery (CABG) has never been reported. Purpose of this study was to investigate the effect of CCC grade on the LVRR event in patients with chronic IHD underwent CABG. Methods: This prospective cohort study was performed in patients with chronic IHD underwent CABG. The CCC was classified using Rentrop collateral score, i.e low CCC grade (Rentrop score 0 and 1) and high CCC grade (Rentrop score 2 and 3).  LVRR event was defined as a reduction in left ventricular end systolic volume (LVESV) of 10% or more, measured by a 3D echocardiography at 1.5 months post CABG compared to the baseline before CABG. Results: A total of 22 patients (81.8% male) with mean of age 58.6 years old were enrolled. LVRR occurred in 50% patients. LVRR event was significantly higher in the patients with high CCC grade than the low CCC grade patients (p=0.009). The high CCC grade increased LVRR event independently (odds ratio=26.67; relative risk=6.93). Conclusions: High coronary collateral circulation may increase left ventricular reverse remodeling event in patients with chronic ischemic heart disease underwent coronary artery bypass surgery. Keywords: coronary collateral circulation; left ventricular reverse remodeling; chronic ischaemic heart disease; coronary artery bypass surgery; 3D echocardiography.