After a short historic introduction, the article describes the total endoprotheses of the knee used in our hospital. This is followed by a description of the case material. The follow-ups of the 51 total endoprotheses of the knee applied between April 1971 and October 1975, covered the following criteria: Pain, extent of mobility, extension deficit, stability and walking performance. The article subsequently reviews the complications occurring with the hinged and hingeless total endoprostheses of the knee. Pain, extent of mobility and stability are evaluated via a system of points, thus enabling an evaluation of the functional results of the individual prostheses. During the following discussion, our results are compared with those of three other follow-ups. Comparisons are not always possible, because the evaluation standards may differ. However, we believe that we can say that our results do not differ significantly from those of the studies against which they were compared. In both cases, the complications are mainly the same. With particular reference to a comparision of the results obtained with the Freeman-Swanson prostheses, the results obtained by Freeman during both periods of time were superior to ours. Our experiences with the hingeless Freeman-Swanson prosthesis are rather better than those obtained with the hinged prostheses according to Shiers ans Guépar, especially with regard to the frequency of loosening and infection. However, it must be borne in mind that the follow-up control times are shorter for the Freeman-Swanson prostheses. We believe that implantation of a hinged prosthesis in joints with severe malpositioning of the axis, severe deformities, and instability, continues to be indicated.