An alcoholic extract of Biophytum sensitivum was studied for its immunomodulatory and antitumor activity. Theextract was 100% toxic at a concentration of 0.5 mg/ml to Dalton’s lymphoma ascites (DLA) and Ehrlich ascitescarcinoma (EAC) cells. B. sensitivum extract was also found to be cytotoxic towards L929 cells in culture at aconcentration of 0.1 mg/ml. Administration of B. sensitivum extract (500μg/dose/animal) could inhibit the solid tumordevelopment in mice induced with DLA cells and increase the lifespan of mice bearing Ehrlich ascites carcinomatumors by 93.3%. B. sensitivum treatment significantly (p<0.001) reduced the tumor cell glutathione (GSH) levels aswell as serum gamma glutamyl transpeptidase (GGT) and nitric oxide (NO) levels in ascites tumor bearing animals.The total WBC count was also increased to 14,087 cells/mm3 on the 12th day in BALB/c mice. The number of plaqueforming cells also enhanced significantly (p<0.001), and bone marrow cellularity and β-esterase positive cells werealso increased by the administration of B. sensitivum extract.