Among cochlear implant candidates there are patients who have abnormal middle and/or inner-ear conditions that make them unsuitable for implantation. Insertion of a foreign body may also be contraindicated in the setting of an existing or potential intracranial communication, or when the ear is prone to infection. Five patients presented with such unfavorable conditions. These included a Mondini dysplasia with persistent cerebrospinal fluid leak, an atretic mastoid with meningocele, chronic otitis media, a transverse petrous bone fracture, and a temporal bone adenoma. All patients underwent subtotal petrosectomies and cochlear implantations. In four cases implantation was performed concomitantly with subtotal petrosectomy, while the remaining case required a two-stage procedure. No complications occurred. The technique is described in detail, and the cases and the indications for surgery are discussed. By obliterating and isolating the tympanomastoid cleft from the outer environment and utilizing the technique of subtotal petrosectomy, a broader spectrum of patients can now be implanted safely.