Two hundred seventy-nine consecutive patients with Stage II osteogenic sarcoma of the appendicular skeleton treated between 1976 and 1986 were studied to identify predictors of long-term survival. Survival was 77% and 73% at 5 and 10 years, respectively, with continuously disease-free survival being 70% and 69%. On univariate analysis, the most significant predictors of survival were the location of the primary lesion, local control of the tumor, and the degree of necrosis in the primary tumor after intravenous neoadjuvant chemotherapy (histologic response). On initial multivariate analysis, similarly, only location and histologic response to chemotherapy predicted disease-free outcome. After statistical control for local recurrence, only histologic response to chemotherapy was retained as an independent predictor, suggesting that in this data set, the location of primary lesion exerted its effect only secondarily through its association with the ability to provide local control. The risk of local recurrence was almost fivefold higher in tumors of the femur than in tumors of other locations (relative risk, 4.6) and, within the femur, was more than threefold higher in the proximal femur than in the distal femur (relative risk, 3.4). None of the other primary tumor or patient characteristics studied yielded independent predictive significance for survival. The rate of failure was almost fivefold as high in those with an incomplete response to chemotherapy compared with those with a complete response to chemotherapy (relative risk, 4.9; 95% confidence interval, 2.2 to 11). Even in those patients with minimal or no necrosis in the primary tumor, ultimately 62% and 54% were disease-free at 5 and 10 years, respectively.