The great variation in the reaction to radiation therapy has long been a source of interest. It is difficult to explain why one patient will become violently ill after radiation therapy while another will get little or no reaction from the identical type of treatment. We have not found it possible to determine accurately before treatment just which patient will respond with radiation sickness. We feel that the region of the body treated, the area of the treatment portals, and the dosage have a definite relationship to the production of this response. Its severity is apparently dependent on some inherent susceptibility in the patient. It appears justifiable to say that a patient suffering from malnutrition, debilitation, and avitaminosis will usually not tolerate radiation therapy as well as a patient in good nutritional balance. Since the maintenance of the physical condition and general well-being of the patient at the highest possible level is the aim of all physicians, it is well for us to treat the patient as well as the disease. The radiologist, usually called as a consultant, is guilty in many instances of allowing the medical care of the patient to rest on the shoulders of the referring physician. All too frequently this means that nutritional balance will not receive adequate attention. This condition should not exist, and the radiologist who accepts a patient for treatment should insist upon an adequate program for the case as a whole, including sufficient food and fluid intake, sufficient rest, and the maintenance of normal body functions in so far as this is possible. After these essentials have been established in the care of the patient, the radiologist should use special methods of treatment and suitable drugs to control the unusual symptoms which may occur. Since radiation sickness is the nemesis of the therapist, it is worthy of careful consideration. The scientific studies, in the decade following 1920, of such workers as Doub, Bolliger, and Hartman (7, 8), Martin and Rogers (20), Denis and Martin (6), Warren and Whipple (33), and others, formed the basis upon which investigations have continued in this field. There have been many theories advanced as to the cause of true radiation sickness (5, 6, 7, 8, 10, 12, 17, 20, 21, 22, 23, 24, 28, 33) and many methods of treatment suggested to alleviate it (2, 3, 10, 14, 15, 16, 19, 23, 25, 26, 34, 36). The multiplicity of suggested causes and of therapeutic procedures bears evidence to the fact that there is no single method for control of this condition. It would be difficult, if not impossible, to administer to the patient all of the specified treatments which have been advocated in the last twenty years. The introduction of the vitamin B1 group as a therapeutic aid by Martin and Moursund (19) in 1937 seems an important step forward in the control of radiation sickness.