This guidance is intended to assist sponsors of clinical trials in determining when a data monitoring committee (DMC) (also known as a data and safety monitoring board (DSMB), a data and safety monitoring committee (DSMC), or an independent data monitoring committee (IDMC)) would be useful for trial monitoring and what procedures and practices should be considered to guide their operation.  When finalized, this guidance will supersede the final guidance for clinical trial sponsors entitled “Establishment and Operation of Clinical Trial Data Monitoring Committees,” issued in March 2006. This draft guidance is not final nor is it in effect at this time.