To investigate the influence of exogenous lactoferrin (LF) on tumor growth, energy and lipid metabolism of Walker-256 carcinosarcoma and to assess genotoxic effects of LF.The study was performed on Walker-256 tumor-bearing rats. Total lipids and phospholipids were determined by thin-layer chromatography. Comet assay was used to investigate the genotoxic effects of LF.Daily i.p. administrations of exogenous LF at concentrations of 1 mg/kg and 10 mg/kg starting from the 4Exogenous LF caused the inhibition of Walker-256 carcinosarcoma growth and a decrease in the microviscosity of plasma cell membranes, and exerted no genotoxicity toward bone marrow cells and peripheral blood of experimental animals.