The results of a specific type of prosthetic reconstruction of the knee (total replacement arthroplasty) after resection of a sarcoma of the proximal part of the tibia in sixteen patients were retrospectively reviewed. The diagnosis was stage-IIB osteogenic sarcoma in nine patients, stage-IIB malignant fibrous histiocytoma in three patients, and stage-IB sarcoma of various types in four patients. The length of tibial resection ranged from 100 to 257 millimeters. Of the eleven patients who were available for functional examination (mean duration of follow-up, sixty-three months), three patients had an excellent result, seven had a good result, and one had a fair result. Of the five patients who were not available for functional testing, one who was doing well was lost to follow-up at eighty months, one had died of metastases at sixteen months, and three had had a secondary amputation for infection or for loosening of the prosthesis.