There was held micro- and ultrastructural study of the liver of the Wistar rats in the dynamics of development of transplantable Walker 256 carcinosarcoma. The regularities of the progression of the tumor process in the form of liver metastases with appearance of intralobular metastases. In the early stages of tumor development it was marked activation of cytotoxic function of the liver with necrosis of tumor lesions accompanied by a decrease of the structural density of metastases. In advanced stages of development of the Walker 256 carcinosarcoma an estimation of parameters of tumor invasion in the liver showed an intensification of these processes with increased severity of inflammatory reactions.