This paper uses the report of the Lipid Research Clinics Coronary Primary Prevention Trial as an example of how clinicians apply the results of clinical trials to their practice. Clinical trials influence practice primarily to the extent that they eventually become incorporated into the generally accepted standard of medical care. To a lesser extent, physicians are influenced by their own interpretation of clinical trial results. Since physicians usually do not have the leisure or the technical expertise to evaluate primary data critically, their conclusions are heavily influenced by the authors' sometimes overoptimistic interpretation of the results. Therefore, practicing clinicians often overestimate the benefits of a therapy and generalize the results of a trial too broadly. Ideally, physicians should base treatment decisions on their knowledge of the pathophysiology of the disease, the mechanism of action of the proposed treatment, and the clinical characteristics of the individual patient while informing their decision with a critical understanding of the results of relevant trials.