We present three cases of acquired deafness, associated with obliterated cochleas, in which the apparently radiologically more favourable side was chosen for implantation. In the first case, because of unexpected obliteration, only a partial insertion was possible. Deteriorating performance and non-auditory stimulation of the facial nerve led to removal of the implant and a contralateral implantation with full insertion under the same anaesthetic gave a good postoperative result. In the second case, CT scanning indicated minimal obliteration, but extensive obliteration was encountered at surgery, which required double-array insertion with a delayed but satisfactory outcome. In the third case, extensive unexpected obliteration was noted at surgery and, in light of the experience gained with the first two cases, it was decided not to proceed but to explore the contralateral side. At surgery on the contralateral side, a patent cochlea was noted with full electrode insertion and an excellent outcome. These cases demonstrate a learning curve for this department and our philosophy now is to explore the contralateral ear rather than accept a partial insertion.