Epinephrine is the most widely used vasoconstrictive drug. However, its radioprotective potential has not yet been studied for radiation-induced mucositis and dermatitis. Other vasoconstrictive drugs induce a radioprotective effect, but are not used because of their severe side effects. We studied the radioprotective effect of epinephrine on the oral mucosa and scalp of the mice. The radiation dose was 20Gy in a single fraction to the head of the mouse. In the group treated with epinephrine ointment, secretion from the oral cavity was slight, body wieght loss was less and hair loss was observed in fewer cases compared to those in the group without of epinephrine ointment. The mechanism is thought to be related to oxygenation. Epinephrine causes vasoconstriction, therefore the blood supply is lowered and the oxygen concentration in the tissue decline. In conclusion, epinephrine is considered to have potential as a radioprotective ointment for mucous membranes and skin.