In this work for the first time we demonstrate the possibility of ribonuclease barnase delivery to HER2-positive human cancer cells in a liposomal form. The principle of loading liposomes with ribonuclease is based on the electrostatic interaction of the protein with the inner surface of the liposomes. The specificity of liposomes to the HER2-receptor is determined by the presence of the anti-HER2-address module DARPin on the outer membrane of the liposome. It was shown that cytotoxicity specific for HER2-positive cells is determined precisely by the presence of an address HER2-specific module on the surface of liposomes, and the severity of the cytotoxic effect correlates with the level of expression of the HER2 receptor on the cell membrane.