Clinical trials may furnish data to conduct economic analyses. An economic analysis requires us to identify all opportunity costs associated with the intervention over the time horizon chosen for the analysis and enumerate the improvements in benefits from the intervention of interest. We review the basic steps used when performing economic studies based on secondary analysis of data from clinical trials using examples from myocardial infarction studies. Different types of economic analyses and the potential contributions of Markov modeling are described. Issues of measuring quality of life, patient utilities, cost of care, and potential sources of cost data are reviewed. The interpretation of incremental cost-effectiveness ratios is discussed and economic benchmarks for defining good and poor value interventions are provided.