Most people with hearing loss can benefit from conventional air-conduction hearing aids, however some people cannot wear these or do not benefit fully from them. A BAHA delivers sound through the skull by vibrations, missing out the outer and middle ears. Hearing loss can occur in both ears (bilateral). In these cases, BAHAs are usually fitted on just one side (unilaterally), but it has been suggested there may be benefits of bilateral BAHAs. The benefits and costs of bilateral compared with unilateral BAHAs and of BAHAs compared with conventional aids or surgery is not known.A systematic review and economic evaluation will be undertaken. Literature will be identified from several sources including electronic databases. Studies will be selected for inclusion using pre-defined and explicit criteria by two reviewers independently. Data will be extracted by two reviewers and the methodological quality of all studies will be assessed using recognised criteria. Data will be synthesised through a narrative review with tabulation of results of included studies. Where possible results will be synthesised through meta-analysis.We will develop an economic model either through adapting an existing model or developing our own new economic model to examine the costs and benefits of BAHAs within the UK. This will use data from our review of studies, advice from clinicians and patient representatives and data from recognised sources