Total parenteral nutrition (TPN) is a clinical adjunct to cancer therapy. But it is difficult to do controlled clinical studies on cancer patients undergoing TPN. We therefore turned to a study of TPN on Buffalo strain rats with and without a Morris 7777 transplantable hepatoma. Our results showed that TPN at higher than normal levels (total parenteral hyperalimentation, abbreviated TPH) supported a gain in body weight of nontumorous rats. In tumorous rats, TPH supported body weight gain and stimulated tumor growth. Detailed analysis showed the TPH of the rats with a large rapidly growing hepatoma did gain body weight associated with fluid retention while the carcass weight decreased. Nor did TPH of tumorous rats significantly reverse the low cell proliferative activity to ear epidermis attributed to the tumor though it did stimulate tumor cell proliferation. Thus TPH by itself did not overcome wasting due to presence of the tumor. Using the hypothesis that uncontrolled gluconeogenesis is linked to cancer cachexia, we combined TPH with inhibition of gluconeogenesis (using hydrazine sulfate) and prevented the carcass weight loss (cachexia) in the tumorous rats. Tumor growth was stimulated by this treatment. Stimulation of cell proliferation in the tumor can, however, benefit chemotherapy using an S phase or cell cycle-specific cytotoxic drug.