A percutaneous device system for long-term intracorporeal access is presented. A technical description of the device is given as well as results from healing in of device dummies and everyday functioning devices both in the short- and long-term perspectives in experimental animals and in human volunteers and patients. Major complications have not been observed by clinical inspection. Histological analyses of the animal experiments indicated that the downgrowth of the epidermal cells was arrested at the most superficial borderline of a preformed cavity region. An increased subepithelial cell density was observed lateral to a moderate sinus tract, but there were no heavy inflammatory cell infiltrations. The clinical success of the implants evaluated appears to be based on the following design factors: (1) selection of titanium as the tissue interfacing surface, (2) surface geometry factors applied, (3) a system of preformed cavities promoting connective-tissue interdigitation, (4) stress relief design of the subcutaneous flange, (5) high-precision surgical instrumentation and method. It is concluded that the results obtained so far are sufficiently promising to justify further controlled clinical trials and extended observation periods.