1. Inhibiting the renin-angiotensin-aldosterone system prevents left ventricular (LV) remodelling after myocardial infarction (MI). 2. The present study was designed to assess the effects of a combination of perindopril and losartan on LV remodelling, cardiac function and serum procollagen type III amino terminal peptide (PIIINP) levels in patients with acute MI. 3. Patients with anterior MI were divided into three groups: (i) MI + perindopril; (ii) MI + losartan; and (iii) MI + perindopril + losartan. After successful intervention therapy, perindopril (2-4 mg daily), losartan potassium (25-50 mg daily) or their combination were administered. All patients received aspirin, clopidogrel and statins, and some patients were given beta-blockers, nitrate and a platelet glycoprotein IIb/IIIa receptor antagonist. Three months later, LV dimensions and LV ejection fraction (LVEF) were measured by ultrasonography. Plasma B-type natriuretic peptide (BNP), serum C-reactive protein (CRP) and PIIINP levels were evaluated using enzyme-linked immunosorbent assay or radioimmunoassay. 4. The baseline characteristics of the three groups were the same. Three months after the initiation of therapy, all patients showed decreased CRP, increased BNP and PIIINP levels and LV dilation and dysfunction. Compared with the two monotherapy groups, patients in the combination group showed significantly lower CRP, BNP and PIIINP levels, less LV dilation and higher LVEF. Serum PIIINP levels were positively correlated with CRP levels (r = 0.597; P < 0.01) and LV end-diastolic volume index (r = 0.543; P < 0.01) and were negatively correlated with LVEF (r = -0.565; P < 0.01). 5. For patients with acute MI, combination treatment with perindopril and losartan significantly inhibited LV remodelling and improved LV function. Inhibition of myocardial interstitial fibrosis may be part of the underlying mechanism.