This study analyzes the OrthoPilot navigation system's (Aesculap, Tuttlingen, FRG) learning curve in beginner vs. experienced centres. We conducted a prospective, controlled, multi-centre study in 13 European orthopedic centres. Overall, 368 total knee replacements (TKR) were included in this study, with 150 TKR performed in experienced centres (control group) and 218 TKR in beginner centres (study group). The study parameters were implantation accuracy, clinical outcome, operation time and complications. No difference was found between both groups, except for operating time which was significantly longer in the study group. However, this increase in operating time disappeared after 30 implantations in all beginner centres. So, we conclude that the system's learning curve levels off at this point. Given the high accuracy of implantation when using the OrthoPilot navigation system, we believe this learning curve to be acceptably low.