Thyroid gland is a unique organ, has a natural avidity for iodine that isn’t manifested in any other tissue of the body. Indeed, oral administration of I131 has been a commonly accepted procedure for treatment of benign and malignant conditions of the thyroid since the 1940s. Patients who will receive radioactive iodine RAI therapy should be provided by comprehensive information about it, to overcome their misconceptions, problems and needs. This book presents a study to assess patients' knowledge, needs and problems among patients undergoing RAI therapy. The study revealed that the thyroid patients had lack of knowledge and need to know about RAI treatment and its precautions, also they complained from physical, psychological, social and financial problems and reported they need help in many areas of them. The nuclear nurse should provide a comprehensive assessment of patients' problems and needs and their informational needs to maximize the effectiveness of RAI therapy. Multidisciplinary team should be collaborating in management of patients undergoing RAI therapy and helping them to overcome their problems and needs