The University of York published a report from the National Institute for Health Research in 2009 that examined the findings of randomised controlled trials (RCTs) relating to the effectiveness (or otherwise) of hypnotherapy.
With regard to the use of hypnotherapy to treat 'generalised or unspecified anxiety', the report stated: "One RCT reported that hypnosis was superior to both music relaxation . . . and no treatment . . . for reducing anxiety scores. However, one RCT reported that hypnosis was no more effective that meditation, and another RCT reported hypnosis was no more effective than no treatment"
The authors' overall conclusion was: "The evidence from current RCTs was insufficient to support the use of hypnosis for the treatment of anxiety".
http://www.crd.york.ac.uk/crdweb/ShowRecord.asp?LinkFrom=OAI&ID=12009103462