This study evaluates the effectiveness of preoperative chemotherapy in osteogenic sarcoma and the subsequent selection of postoperative adjuvant chemotherapy based on the response of the primary tumor. From June 1978 to October 1980, 57 patients with primary osteogenic sarcoma were treated with high-dose methotrexate (HDMTX) and citrovorum factor rescue (CFR), Adriamycin, and the combination of bleomycin, cyclophosphamide, and dactinomycin (BCD) for 4-16 weeks before definitive surgery. Histologic examination of the resected primary tumor determined the effect of preoperative chemotherapy, with many tumors showing greater than 90% necrosis. Patients with a favorable response (Grades III and IV) continued on the same regimen postoperatively (regimen B), while those with a poor response (Grades I and II) were switched to a regimen containing cisplatinum and Adriamycin (regimen A). The overall disease-free survival rate was 93% at a median of 20 months, with 53 patients remaining free of recurrent or metastatic disease. The study highlights the importance of thorough histologic examination in predicting survival and identifying patients who can benefit from alternative postoperative adjuvant chemotherapy.This study evaluates the effectiveness of preoperative chemotherapy in osteogenic sarcoma and the subsequent selection of postoperative adjuvant chemotherapy based on the response of the primary tumor. From June 1978 to October 1980, 57 patients with primary osteogenic sarcoma were treated with high-dose methotrexate (HDMTX) and citrovorum factor rescue (CFR), Adriamycin, and the combination of bleomycin, cyclophosphamide, and dactinomycin (BCD) for 4-16 weeks before definitive surgery. Histologic examination of the resected primary tumor determined the effect of preoperative chemotherapy, with many tumors showing greater than 90% necrosis. Patients with a favorable response (Grades III and IV) continued on the same regimen postoperatively (regimen B), while those with a poor response (Grades I and II) were switched to a regimen containing cisplatinum and Adriamycin (regimen A). The overall disease-free survival rate was 93% at a median of 20 months, with 53 patients remaining free of recurrent or metastatic disease. The study highlights the importance of thorough histologic examination in predicting survival and identifying patients who can benefit from alternative postoperative adjuvant chemotherapy.