Administration of herbal drugs to cure diseases in humans is since time immemorial. Each and every civilization has its own culture and medicine, are called as traditional systems. Siddha system of medicine is one of the traditional system belongs to Dravidian race belongs to southern part of India. This system of medicine is using herbals, metals and minerals as the raw drugs to make medicines. Recent scientific trends insisting that administration of metals in human usage should undergo the toxicity studies. Amirtharasa mathirai is one of the siddha formulation made up of heavy metal mercury and sulphur. Amirtharasa mathirai (ARM) is studied for acute toxicity. The results are the ARM did not exhibit any mortality in mice. No behavior changes and weight reduction of mice in this study. Reflexes were found to be normal before and after the drug administration. In necropsy, all the internal organs are appeared normal. Hence the siddha formulation ARM is safe and recommended for human usage.