Over the last 20 years, the development of meta-analysis has been aimed at obtaining objective synthesis of the available results on specific research questions. The main achievements of meta-analysis include the application of techniques to perform systematic literature searches and to obtain unbiased selection of studies, data extraction and pooled estimates of effect. This paper discusses the methodologic steps to follow when conducting a meta-analysis, with emphasis on study selections, data collection and statistical methods to combine the results from individual studies. We also present a set of guided questions as an aid to critically evaluate the conclusions of published meta-analyses. The application of meta-analytic techniques to cardiology is illustrated using a meta-analysis of the randomized controlled trials of angioplasty versus bypass surgery in the management of patients with ischemic heart disease.