9019 Objectives: Based on a previous monocentric phase II trial with neoadjuvant ifosfamide CDDP based regimen in adults, a multicentric phase II study of neoadjuvant chemotherapy for osteosarcoma of patients over 16 years was initiated in 1993 in the French Sarcoma Group. Methods: Four preoperative courses of ifosfamide 9g/m2 in 3 days and CDDP 100mg/m2 on day 4 (SHOC) were given, followed by local treatment. Post operative chemotherapy was adapted according to pathological response, doxorubicin (60mg/m2) being added (HOCA regimen) in patients with tumors >10% of viable tumor cells. Pathological response rate) was the principal objective of the study. Results:Between January 94 and June 1998, 63 pts were included, 14 females, 49 males, with a median age of 27 (range: 16–63). Primary tumors were femur (39%), tibia (12%), humerus (10%), flat bones (28%). Grade 3 and 4 neutropenia, febrile neutropenia, thrombopenia and rehospitalisation occured after 58%, 17%,17% and 22% of courses of SHOC and 76%, 28%,47%, 47% of the courses of HOCA. Respectively 13%, 19%, 24%, 32% and 12% of patients had grade 4, 3, 2, 1, and non evaluable pathological response to preoperative chemotherapy. Good pathological response was observed in 20 (31%) of included patients. With a 68 months median follow-up, overall and progression-free survival at 5 year are 54% and 47% both (PFS 72% and 35%, and OS 81% and 50% respectively for good and poor responders) Conclusions: In adult patients, preoperative high dose ifosfamide and CDDP (SHOC) regimen yields response rate and survival comparable to that achieved with doxorubicin containing regimen. No significant financial relationships to disclose.