Here we present the results of comparative immunoenzyme assay of the initial serum levels of VEGF in breast cancer patients (stages T 1N0M0 and T2N0M 0) and apparently healthy women (controls). It was found that VEGF concentrations in the serum of patients with breast cancer stages T 1N0M0 and T2N0M 0 significantly surpassed the control levels. Increased levels of VEGF surpassing the threshold values were more often observed in patients with T2N0M0 breast cancer compared to patients with T1N0M0 tumor. At the same time, this marker cannot be used in the diagnostics of this disease because in only 21.4% patients serum level of VEGF surpassed the upper boundary for this growth factor observed in the serum of control women. Serum concentration of VEGF in patients with stages T1N 0M0 and T2N0M0 breast cancer did not depend on patient's age and reproductive function and receptor status of the primary tumor (estrogen and progesterone receptors), but was closely associated with tumor histogenesis and differentiation degree. Significantly higher levels of VEGF were observed in patients with lobular infiltrative breast carcinoma compared to patients with ductal tumors and in patients with low-differentiated tumors compared to highly and moderately differentiated tumors. High initial concentrations of VEGF (>300 pg/ml) were more often detected in patients with T2N0M0 breast cancer developing relapses within the first 3 years of follow-up compared to patients without relapses during the corresponding period (p=0.001). These findings suggest that serum level of VEGF in patients with T2N 0M0 breast cancer before treatment can be used as an additional marker in parallel with standard clinical and morphological signs of the disease for more precise prognosis of early relapse (during the first 3 years of follow-up). © 2009 Springer Science+Business Media, Inc.