ABSTRACT :- Virechana Karma is the process of expelling doshas through Adhobhaga i.e. Guda . It is the detoxifying procedure that should be performed only after doing snehan (both internally and externally) and swedan. Virechan is indicated in multiple conditions like Pitta Pradhana Vyadhi’s like Pandu and Kamala, Rakta Pradoshaja Vyadhi like Kustha, Visarpa and Raktapitta , Amlapitta, Prameha, Amavata, Hridayaroga, Pakshaghata, Sthaulya. In this article, we are describing Mode of action of Virechan karma according to Ayurveda and Modern Science. We will see how modern science is helpful in understanding the facts related to Virechan karma. We will see the importance and need of understanding mode of action in this article.