Translation of medical evidence into practice has not kept pace with the growth of medical technology and knowledge. We present three case studies--statins, drug eluting stents and bone marrow transplantation for breast cancer--to propose a framework for describing five factors that may influence the rate of adoption. The factors are: validity, reliability and maturity of the science available before widespread adoption; communication of the science; economic drivers; patients' and physicians' ability to apply published scientific findings to their specific clinical needs; and incorporation into practice guidelines.