Background: The most potentially useful systematic reviews summarise the results of at least one high quality RCT. Within any particular sphere of practice the potential for producing high quality systematic reviews is dependent on finding appropriate RCTs.

Objectives: To determine which areas of practice within Otolaryngology Head & Neck Surgery have been evaluated by RCTs.

Methods: We searched the Cochrane Ear, Nose & Throat Disorders Group trials register (29 March 2004 and again immediately prior to presentation) using free text synonyms based on 22 pre-selected, clinically important topics within the Group s scope.

Results: Of the 9816 citations in the Specialised Register, 8668 (88%) were identified by the search. Of these, 5848 (86%) were RCTs. Of these, 25.8% related to head & neck cancer, 36.7% to rhinological topics, 25.5% to otological topics and 12% to those related to the larynx or pharynx. Nearly two-thirds of the citations related to one of three topics: head & neck cancer (25.8%), rhinitis (27.8%) or otitis media (12%), with the first two accounting for over 50% of the citations.

Very few trials - less than 5% of the total in each case - were identified in a number of important clinical areas, including tinnitus, vertigo and otitis externa.

Conclusions: Otolaryngology head & neck surgery is a broad field covering benign and malignant ear, nose, throat and neck disorders. Despite this breadth, most RCTs have been undertaken in a limited number of areas, while in some important clinical areas there are few, if any RCTs. This study will therefore help us to map those areas of our scope where the evidence is rich and systematic review would be productive and informative, and also to highlight those areas where there are clear gaps in the evidence base and future trials should be encouraged.

Acknowledgements: The authors would like to thank all those volunteers who have contributed citations to the trials register.