Trimetazidine has been shown to improve angina pectoris and left ventricular (LV) function in diabetic patients with ischaemic cardiomyopathy. The objective of this study was to evaluate the effects of trimetazidine on recurrent angina pectoris and LV structure after drug-eluting stent (DES) implantation in elderly multivessel coronary heart disease (CHD) patients with diabetes mellitus (DM) and a left ventricular ejection fraction (LVEF) of a parts per thousand yen50 %. This was a single-centre, prospective, randomized, double-blind evaluation study. Between January 2010 and September 2010, 700 CHD patients with DM who were aged a parts per thousand yen65 years and undergoing coronary angiography at An Zhen Hospital (Beijing, China) were recruited and prospectively randomized to receive trimetazidine (20 mg three times daily) or placebo after DES implantation as an addition to conventional CHD treatment. The primary end points were the incidence of recurrent angina pectoris and measures of various echocardiographic parameters, which included LVEF. At 2-year follow-up, patients in the trimetazidine group (n = 255) showed significant improvements in the incidence (P = 0.024) and severity of angina pectoris, compared with the control group, as well as silent myocardial ischaemia (P = 0.009) and angina pectoris-free survival (P = 0.011). LV function and structure in trimetazidine-treated patients were relatively stable at 2-year follow-up, while they deteriorated in the control group (n = 255) with a significant difference between groups (all P < 0.01). The E peak to A peak (E/A) ratio in trimetazidine-treated patients and in the control group decreased after 2 years; the E/A ratio in trimetazidine-treated patients was slightly better than that in the control group, without a significant difference (P = 0.170). There was no significant difference in event-free survival for the composite end point including death, myocardial infarction, cerebrovascular accident (P = 0.422) and subsequent revascularization (P = 0.073). Adjunctive therapy with trimetazidine after DES implantation can have a beneficial effect on recurrent angina pectoris as well as LV function and structure in elderly multivessel CHD patients with DM.