BACKGROUND: The effect of angiotensin converting enzyme (ACE) inhibitors on symptoms in patients with left ventricular systolic dysfunction (LVSD) is controversial. AIMS: To perform a meta-analysis of studies evaluating effect of ACE inhibitors on New York Heart Association (NYHA) class in patients with LVSD. METHODS: Individual data from 10389 patients in NYHA classes I-IV from four large long-term studies (2-4-year follow-up) and summary data from 2302 patients in NYHA classes II-IV from 16 short-term studies (3 months follow-up) were meta-analysed to assess changes in NYHA class. RESULTS: The large long-term studies showed a significant improvement in the worst NYHA classes (classes II-IV compared to class I) in the ACE inhibitor arm versus placebo, odds ratio (OR) = 0.875 (0.811-0.943) p = 0.0005. This effect was only present in studies which included patients with chronic heart failure and was particularly pronounced on deterioration to the worst NYHA class IV, OR = 0.66 (0.52-0.84) p = 0.001. There was no effect in the studies which included patients after myocardial infarction. The short-term chronic heart failure studies showed a significant improvement in NYHA class; OR for improvement of at least one NYHA class was 2.11 (1.48-2.98, 95% CI) p < 0.0001. CONCLUSION: ACE inhibition significantly improves symptomatic status measured as NYHA classification in patients with chronic heart failure.