To assess the economic attractiveness of clinical research, this study measures the cost-effectiveness of seven selected randomized trials. The model considers the cost of performing a trial and the benefits to the health status of a target population one could expect before the trial was performed. The incremental cost-effectiveness for performing the trials ranged from a low of $2 to $3 per life-year saved for a trial of aspirin in unstable angina to a high of $396 to $685 per life-year saved for the randomized trial portion of the Coronary Artery Surgery Study. These ratios were substantially lower (ie, more economically attractive) than the cost-effectiveness ratios associated with performing interventions of proved effectiveness. This study shows that a selected group of clinical trials, some of which were controversial and expensive, were indeed a good investment. This information may be helpful to policymakers who consider allocating funds to biomedical research.