In the over five years since FDA finalized “Guidance for Clinical Trials Sponsors: Establishment and Operation of Clinical Trial Data Monitoring Committees,” there have been a number of methodological and scientific developments that could cause the reexamination of the basic tenets and the details of the guidance. The main points of the DMC guidance are briefly reviewed. The independence of the DMC and of a third-party statistician, which were a bit controversial when the draft guidance first came out, is revisited. In the past few years a great deal more attention has been focused on enrichment and adaptation of clinical trials. Issues of verifiable firewalls and logistical problems are discussed. The FDA guidance has an expiration date of June, 2012.