The initial levels of soluble Fas antigen (sFas), leptin, and vascular endothelium growth factor (VEGF) were measured in the sera of 100 patients with ovarian cancer and benign tumors and in 60 healthy women aged 28-65 years. Serum levels of sFas and VEGF were elevated in the total group of patients with ovarian tumors, while leptin levels were the same as in healthy women. The studied parameters did not depend on the age of patients and healthy women. The levels of sFas and leptin were virtually the same in benign and malignant ovarian tumors, while VEGF concentration was higher in patients with ovarian cancer. The mean serum levels of sFas, VEGF, and leptin in patients with poorly and moderately differentiated serous ovarian cancer were 2-fold higher than in well-differentiated tumors (p<0.05), while serum concentrations of sFas and leptin increased with the disease stage progress in patients with ovarian cancer (p<0.05). According to the data of unifactorial analysis, the increase in serum levels of sFas and VEGF in ovarian cancer patients correlated with short duration of the relapse-free period. Multifactorial analysis showed that the disease stage (p=0.006), presence of ascites (p=0.03), VEGF concentration (p=0.02), and the sFas/leptin coefficient (p=0.045) are highly significant independent factors for predicting the relapse-free survival of patients with serous ovarian cancer.