This study revealed different sensitivity of brain glioma cells (n=62) to the a-interferon (a-IFN) straight action in vitro depending on cytokine’s concentration. The glioma’s sensitivity to the cytotoxic a-IFN action was reduced according to the growth of the tumor malignancy level. 45% of the benign astrocytomas, 30% of III anaplastic degree astrocytomas and 27,3% of IV anaplastic degree astrocytomas demonstrated the high sensitivity to a-IFN. Minimal tumor cells sensitivity to the a-IFN antitumor action was observed in 36,3% of glioblastomas, 25% of III anaplastic degree astrocytomas and 15% II anaplastic degree astrocytomas.