Background: The UK Database of Uncertainties of Effects of Treatments (UKDUETs) has been established in the UK to publish uncertainties that cannot currently be answered by referring to reliable up-to-date systematic reviews of existing research evidence. UKDUETs draws on three main sources to identify uncertainties about the effects of treatments: a) patients’, carers’ and clinicians’ questions about the effects of treatments; b) research recommendations in reports of systematic reviews and clinical guidelines; and c) ongoing research, both systematic reviews in preparation and new ’primary’ studies. The Ear Nose and Throat and Audiology Specialist Library (ENTSL) was invited to contribute to UKDUETs in January 2007. The library collection of high quality systematic reviews was an obvious starting point for identifying uncertainties from research recommendations and ongoing research. Objectives: To harvest therapeutic uncertainties in ENT and audiology from an extensive collection of systematic reviews. Methods: An exhaustive audit of ENTSL systematic reviews, relating to all stages of the clinical process, was conducted. Treatment-related reviews with adequate reporting were extracted as potentially eligible for UKDUETs. Eligible reviews were coded by age since publication, to identify those in need of updating, and by uncertainty status. Once a potential uncertainty was identified, further searching for reliable up to date reviews and ongoing research was conducted to verify its uncertainty status, prior to creating a UKDUETs record. Results: See Figure 1. Conclusions: Therapeutic uncertainties exist in a wide range of conditions both within the specialty of otolaryngology and, by implication, all other specialties. These can be identified from published systematic reviews as well as from questions arising in the course of patient care. A significant number of seemingly conclusive but methodologically flawed systematic reviews fail to acknowledge ongoing uncertainties that need to be addressed by further reliable research.