Tumor necrosis following preoperative chemotherapy in patients with osteosarcoma is a predictor of overall survival. With modern therapies, 45% of patients are expected to achieve more than 90% tumor necrosis. Investigators at the authors' center, however, increasingly noted that patients were experiencing inferior necrosis responses. A retrospective study of treated patients at the center was undertaken to examine this. The purpose of this study was to determine (1) whether the number of patients with favorable histological responses had changed over time and (2) whether the percentage of patients with favorable responses was similar to published outcomes. Chart reviews were performed on patients treated from 1993 to 2003 according to the Pediatric Oncology Group 9351, regimen A protocol. Twenty-one patients met all eligibility requirements; 52% of patients had more than 90% necrosis. No correlation existed between degree of necrosis and year of treatment (r = 0.06; P = .8). Patients with osteosarcoma treated at the authors' institution have comparable tumor necrosis responses to published outcomes, and no change occurred over time. This study stresses the importance of rigorous retrospective reviews before implementing treatment changes.