Abstract: The purpose of this study was investigating experimentally the possible antitumor effect and antioxidant role of methanol extract of Triumfetta rhomboidea (METR) leaves against DaltonοΏ½s ascites lymphoma (DAL) bearing Swiss albino mice. The METR administered at the doses of 100, 200 mg kg 1, in mice for 14 days after 24 h of tumor inoculation. The effects of METR on the growth of murine tumor, life span of DAL bearing mice were studied. Hematological profile and liver biochemical parameters (lipid peroxidation, antioxidant enzymes) were also estimated. Treatment with METR decreased the tumor volume and viable cell count there by increasing the life span of DAL bearing mice. METR brought back the hematological parameter more or less normal level. The effect of METR also decreases the levels of lipid peroxidation and increased the levels of glutathione (GSH), superoxide dismutase (SOD) and catalase (CAT). The present work indicates that the methanol extract of Triumfetta rhomboidea exhibited significant antitumor and antioxidant activity in vivo.