OBJECTIVE In order to increase the number of intracochlear electrodes to be inserted into a totally obliterated cochlea a special implant has been developed in collaboration with Cochlear Ltd. The implant features two separate electrode carriers containing 11 and 10 active electrodes, respectively, and a reference electrode on the receiver stimulator package. The potential stimulation modes include monopolar and bipolar stimulation as well as stimulation between both arrays. METHODS A cochleostomy at the round window provides access to the scala tympani. Newly formed bone is removed as far as the anterior portion of the basal turn. Care is taken to identify and preserve the osseous border of the cochlea. A second cochleostomy is performed immediately caudal to the cochleariform process after removal of the incus. New tissue can be removed here in the same way. The two electrode carriers are then placed into the first and the second turn respectively. The remaining procedure corresponds to the procedure for cochlear implantation in cases in which the cochlea is not obliterated. METHODS For the purpose of a clinical study n = 10 patients aged between 32-66 years with an obliterated cochlea were fitted with a double array cochlear implant. All patients showed signs of total obliteration of the basal turn either in preoperative imaging or during surgery. Intraoperative inspection revealed that the second turn was not obliterated in 4 of 10 patients. POSTOPERATIVE RESULTS: Postoperatively, a standard test battery was used to determine auditory performance over a period of time. All patients achieved significantly better speech understanding due to the additional apical electrode array. No complications occurred. CONCLUSIONS In cases involving an obliterated cochlea, the number of intracochlear electrodes can be increased with the double array implant. As a result, the patients achieve significantly better auditory results.