Erythema multiforme as a reaction to irradiation is a distinct clinical entity. We have been able to find reports of 47 previous cases and have added 7 cases of cutaneous reactions after radiation therapy. Two developed after orthovoltage and 5 after telecobalt 60 therapy. Treatment should include temporary cessation of irradiation, use of topical medications, administration of antihistamines, and systemic administration of corticosteroids if the eruption and systemic symptoms are severe enough to warrant this form of treatment.