Abstract: The siddha system of medicine uses a fascinating combination of herbs, minerals and metals and to promote good health and longevity. Kiranthi mega chooranam (KMC) is one of the Siddha formulations which are indicated as an effective drug for various diseases. Acute Oral Toxicity study and Long term toxicity study in vivo toxicity studies were carried out on Kiranthi Mega Chooranam (KMC) by World Health Organization (WHO) guideline for testing traditional medicines. In Acute toxicity study there was no abnormal signs reported at the dose level of (2000 mg/kg b.wt) within 24-72 hours in wistar albino rats.