Clinic a lTr i a l s.g ov R esult s Data b a se — Update a nd Issuesn engl j med 364;9nejm.orgmarch 3, 2011853The ClinicalTrials.gov trial regis­try was launched more than a decade ago. Since that time, it has been evolving in re-sponse to various policy initiatives. The registry now contains information on more than 100,000 clinical studies and has emerged as a key element of many public health policy initiatives aimed at improving the clinical research enterprise. In 2008, a database for reporting summary results was added to the registry. In this article, we pres-ent an update on relevant policies, summarize the structure and contents of the results database, and show how ClinicalTrials.gov data can be used to gain insight into the state of clinical research