Intensified adjuvant chemotherapy increased the 4-year metastasis-free survival probability from 50% (COSS-77) to roughly 80% (COSS-86). Preoperative chemotherapy was found without recognizable hazard and promoting conservative surgery. Following resection the local failure rate ist significantly higher than after demolitive procedures, including rotation plasty (10.5% vs. 2.5%). Local failures bare a very poor prognosis (19/23 DOD). The acute therapy related mortality is less than 3%. Late toxicities like ototoxicity and cardiotoxicity are intriguing and deserve increased attention. The management of the osteosarcoma patient is a complex and difficult interdisciplinary task which is best performed in centers experienced in the treatment of malignant musculo-skeletal tumors.