Cauterization (Kai) is an ancient medical practice and one of the mode of Ilaj-bit-tadbeer (regimenal therapy) in Unani Medicine. It has been long forgotten in Unani practice due to perceived notion of pain and suffering associated with it. As per quoted in Sahih Bukhari that The Prophet of Allah (peace and blessings of Allah be upon him) recommended healing through branding with fire (cauterizing) but forbid its practice probably due to pain. However, even after coverage of pain through anesthesia and analgesic drugs, cautery (Kai) is still less practiced in Unani medicine. This paper briefly reviews the basic aspect of cauterization in Unani medicine.