A consensus is developing that rich data routinely gathered by health sytems should be used to assess and improve the effectiveness and cost effectiveness of health care interventions, including the pharmaceutical interventions.  There is often a disparity between a medicine's efficaciousness in clinical trials and its effectiveness in practice.  Unforseen outcomes such as adverse effects are often only revealed by retrospective observational studies.  This report gives an overview of patient level practice data routinely collected by OECD and EU countries and included: what is collected; methods of collection; barriers to collection and useage.