Breast cancer is the second most frequent cause of death by cancer. In Romania, its incidence is around 4200 new cases per year and the mortality is around 2500 cases per year. During the past few years a great number of anti-neoplastic therapies with higher specificity and efficiency were developed. Monitoring the effects of these polychemotherapies is of great importance together with the study of their influence on cellular metabolism. The purpose of the study was to establish the changes in the cellular energy metabolism and apoptotic potential in the anti-neoplastic therapy with bevacizumab. The results obtained show that the apoptotic potential of malignant cells increases significantly during the anti-angiogenic treatment, with reduction of tumor vasculature and that the mitochondrial apoptotic pathway is activated by releasing cytochrome c from the mitochondrial inter-membrane space.