Between January 1995 and December 1999, 11 patients with synchronous multifocal osteosarcoma (SMO) received neoadjuvant treatment with high-dose methotrexate, cisplatinum, Adriamycin, and ifosfamide. After primary chemotherapy in 4 patients who had only two bone localizations, it was possible to treat all tumor foci locally. The remaining patients, with more than three bones involved, were treated surgically only in 3 cases at the primary site, while secondary lesions did not receive any treatment. The final results of our study were disappointing. All patients died of the tumor 6 to 24 months after the beginning of treatment (mean 11.9 months). Nevertheless, the survival time of the 4 patients with locally treated lesions was significantly longer than the one of 7 patients in whom the secondary lesions were not locally treated (18.2 vs 9.1 months; P