An ethanolic herbal extract residue was prepared from the seeds of premature fruits of Terminalia arjuna Linn. Different concentrations of it were tested against 1 x 10⁶ million Dalton's Lymphoma Ascites (DLA) tumour cells. At a 200 μg/ml concentration it registered 90% toxicity. Then its effect on the lifespan of mice with DLA tumour cells was studied. At high and low dosages of 50 and 10 mg. b. wt. kg-1 of herbal extract residue, it exhibited 87.5% and 60.4% increase in the lifespan, respectively. Blood parameters such as percentage Hb, RBC and WBC counts were conducted with tail vein blood samples. Hb and RBC counts of treated mice were higher than that of tumour bearing mice, while WBC counts were lower. This is a good index of tumour recovery. Further studies were carried out on mice with solid tumours to record volumes, along with a lifespan study. Low dosage of the herbal extract residue was able to control the tumour volume 35.1% and 32.9% increase in the lifespan was noted both at high and low dosages, respectively.