As a result of the increase in the use of computed tomography and the possibility of demonstrating very small structures, x-ray diagnosis is becoming more and more important in investigating complications after examined in patients as well as cadaver temporal bones by using high resolution middle ear computed tomography: 1. autologous/allogenic ossicular implants, 2. alloplastic implants made of ceramic, plastic or metal. As can be seen from our investigations the homografts and some of the implants are easily identifiable (autologous/allogenic ossicular implants, Ceravital and Frialit PORP/TORP and metal devices), are only partly identifiable (Fisch-Tef Platinum and Stainless Steel as well as Titan stapes pistons), hardly or not at all identifiable (PORP/TORP and stapes pistons made of plastic, e.g. teflon, silicone, plasti-pore). The same applies to ventilating tubes. Thus the position in the middle ear of metal tubes which have slipped can be seen clearly, whereas plastic tubes cannot be seen so well. It is of clinical importance that prosthesis dislocation is visible in CT so that should complications occur it is better possible to determine whether revision surgery is necessary. As, however, identification of various devices in CT is still not satisfactory, the manufactures must soon fulfil our demands for a contrast agent to be added to prosthesis.