Abstract. Despite its effectiveness as an antineoplastic drug, doxorubicin (DOX) is usually associated with cardiotoxicity. Lovastatin (LOV), a hypolipidemic agent used in the clinic, has been demonstrated to have antitumoral and antimetastatic effects in murine models. Since the two agents arrest tumor cells in different phases of the cell cycle and induce apoptosis, the goal of this study was to examine the efficacy of a combination therapy with LOV and low doses of DOX, in an attempt to obtain an improved antitumoral effect devoid of toxicity, by using a rat B-cell lymphoma and a mouse mammary tumor. In the two models, the combined treatment showed a synergistic antitumoral effect, which is mainly ascribed to an increased apoptotic response elicited by a LOV/DOX combination than either agent alone. The therapeutic benefit demonstrated by the combination treatment is further emphasized by the lack of toxicity.