Objective: The aim of this study was to evaluate the audiological performance of the ADHEAR system and to compare it with a softband BAHA system in adults with middle ear disease. Study Design: Prospective, single-subject, repeated-measures study Setting: Monocentric study Participants: In 23 patients with mild to moderate isolated conductive or combined hearing loss (CHL) the ADHEAR system was tested, where 12 of them were outside of the ADHEAR indication. In ten patients, testing was performed with the ADHEAR system and a softband BAHA system. A control group consisted of 10 patients with bilateral artificial occluded ear canal. Main outcome measures: Air and bone conduction thresholds and free-field monosyllable speech intelligibility thresholds in quiet and in noise were measured and evaluated in an unaided situation and aided situation. Furthermore, an ADHEAR questionnaire was assessed. Results: In patients with a middle ear disease compared to the unaided situation, the aided situations with the ADHEAR system and the softband BAHA system led to a significant improvement of speech intelligibility in quiet and in noise. In terms of the ADHEAR questionnaire, using the ADHEAR system patients reported about an improvement in sound localization, sound quality and speech intelligibility. Conclusions: The results show that patients with middle ear disease can benefit from the ADHEAR system, even if their hearing loss is outside of its indication. Outside the indication criteria of the ADHEAR system, it can be an option.