The deleterious effects of ionizing radiation upon the normal tissues of the larynx, even when it is not the specific target of the radiation therapist, are always apparent to the observant and experienced laryngologist. On occasions they are so marked as to obscure the diagnosis of concomitant persistent or recurrent cancer. There is a direct relationship between the number of rads delivered and the severity of the subsequent radiation reaction. A system of classifying such reactions is proposed. Grade 0 is normal. Grades I and II are expected. Grades III and IV may be considered complications and require specific and even energetic treatment. In grade IV reactions, which require operative intervention, laryngectomy may be the treatment of choice.