Objective: Quantify the improvement and impact of the active middle ear implants (AMEIs) on a moderate-to-severe mixed hearing loss population. Study Design: Retrospective study on the indications and results obtained by individuals implanted with the AMEI. SettingS: Tertiary referral center. Patients: Thirteen adult patients with moderate-to-severe hearing loss were evaluated. Air and bone conductive pure tone audiometry and disyllabic word discrimination was performed before and after surgery. The follow-up period was from 5 to 64 months. INTERVENTION: Surgical implantation of the AMEI. MAIN OUTCOME MEASUREMENT: Auditory performance analyzed using pure tone and speech audiometry with AMEI off and on. Results: The average auditory gain in the frequency range 0.5 of 6 kHz was 44.07 dB. The average AC audiometric performance after activating the device is significantly better than the preoperative BC performance in 10 of 13 patients, with an average gain of 11.3 dB. Speech audiometry performance using disyllabic words showed a significant improvement. The detection threshold reduced significantly, from 65 to 24 dB (p = 0.012) with the AMEI. The speech recognition score at 65 dB SPL also showed a significant improvement from 28% to 90% post surgery (p = 0.004). The maximum speech recognition score also improved post surgery, from 56% to 93% with the AMEI (p = 0.023). Conclusion: The AMEI is considered an appropriate device to be used by patients with BC losses up to 70 dB, provided that hearing levels are present in all frequencies between 0.5 and 4 KHz, and the speech recognition percentage is above 60% in the ear chosen for implantation.