Among vishas, Tamra is considered as more poisonous, because, it produces eight toxic effects, such as Bhrama, murcha, vedana, sweda, kleda, vanti aruchi, chittasantape. Copper toxicity leads to heamaturia, glomerulonephritis, gastro-intestinal distwbances, peripheral neuritis, and circulatory collapse, paralysis of limbs and atrophy of muscles, coma and even death. In spite of these properties Tamra Bhasma is widely used in the formulations like Arogya vardhini vati, Laxmi Vilasa Rasa, Hrudayamava rasa, Chandrakala Rasa, etc, which are commonly being practiced. Still there is a dilemma regarding safety and efficacy of Tamra bhasma. To establish its safety an experimental study was conducted on Swiss albino mice (weight 24-30 gms) of both the sexes and its LD5o, Oral acute & sub acute toxicity were assessed. . Toxicity study result shows that in LD5o, the doses ranging from 2orng-Lo-12 gm are observed as non-fatal. Oral acute toxicity study also shows rio mortality or toxic effects. In sub acute toxicity study all animals in all the 4 groups were normal, active and healthy during observational period. It is observed that, the medicinal group of 350 mg has shown alteration in biochemical findings i.e. WBC differential count showed increased percentage of Lymphocytes and decreased percentage of Polymorphs in blood.