This report describes the results of 17 arthroplasties of the hip joint for tumors or metastases in the proximal part of the femur and 3 arthroplasties of the shoulder joint because of tumors in the proximal humerus. Based on case reports the paper discusses the indication in the case of malignant, potentially malignant and benign primary bone tumors and in the case of metastases. In addition principles for the construction of suitable hip and shoulder prostheses are cited, whereby the partial joint replacement continues to retain its justification beside total replacement. While the results of the hip arthroplasty proved satisfactory, the results of the corresponding operation on the shoulder are less satisfactory and urge to exercise more restraint in the operative indication.