Endostatin, placental growth factor, and fibroblast growth factors-1 and -2 in the sera of patients with primary osteosarcomas. Serum levels of endostatin, placental growth factor (PlGF), and fibroblast growth factors-1 and -2 (FGF-1 and FGF-2) were measured in 58 patients with primary osteosarcomas before therapy and in 21 healthy subjects. The incidence of serum FGF-1 in bone tumors was 2.5 times higher than in healthy individuals (p=0.004); significant levels of FGF-2, PlGF, and endostatin were detected in all examined subjects. The mean serum level of endostatin in healthy individuals was significantly lower than in the total group of patients with bone tumors (p=0.005). The level of FGF-1 in osteosarcomas was significantly higher than in chondrosarcomas (p<0.05). No appreciable differences in FGF-2 levels were detected in patients with tumors of different histological structure. The mean serum content of PlGF was virtually the same in healthy individuals and patients with bone tumors. A significant relationship between serum PlGF level and maximum tumor size (p=0.008) was detected in osteosarcoma. No relationships between the levels of FGF-1, FGF-2, PlGF, and endostatin were detected in healthy subjects and patients with primary tumors of the bones. Differences in 3-year overall survival values of patients with bone sarcomas with different initial serum levels of FGF-1 and endostatin were detected.