The need for a standardized system of end result reporting of various surgical alternatives after limb salvaging and ablative procedures for musculoskeletal tumors was clearly recognized during the first International Symposium on Limb Salvage (ISOLS) in 1981. During the ensuing four biannual symposia, there has been an ongoing developmental experience with a system extensively field tested in 1989 by the Musculoskeletal Tumor Society (MSTS). This system of functional evaluation has been adopted by the MSTS and ISOLS for their joint studies and program presentation. In brief, the system assigns numerical values (0-5) for each of six categories: pain, and function and emotional acceptance in upper and lower extremities; supports, and walking and gait in the lower extremity; and hand positioning, and dexterity and lifting ability in the upper extremity. Demographic information and a patient satisfaction component is included. A numerical score and percent rating is calculated to allow for comparison of results. The system has been field tested in 220 patients with low (+/-) interobserver variability. It was well accepted by the participants, and its usage is recommended by the MSTS to facilitate valid comparative end result studies of musculoskeletal tumor reconstructions.