Since October 1973, 185 patients 21 years of age or younger with primary osteogenic sarcoma of an extremity were treated with adjuvant chemotherapy. Twenty-five of the first fifty-two patients (48%) have remained free of disease for a median of 7 years. In the next chemotherapy protocol most patients had chemotherapy prior to amputation or resection, during which time the dose of high-dose methotrexate was escalated in many patients to that needed to shrink the primary tumor. For a median of 4 years 43 of 54 patients (80%) have remained free of disease. In the current protocol, the response of the primary tumor to chemotherapy with high-dose methotrexate was used to select postoperative adjuvant chemotherapy for the patient. With the latter approach 73 of 79 patients (92%) have remained continuously free of disease for a median of 2 years. This experience demonstrates the value of chemotherapy in increasing the cure rate in osteogenic sarcoma and that the response to preoperative chemotherapy can help select postoperative chemotherapy to produce an even higher potential cure rate for osteogenic sarcoma.