Background: Radioactive iodine therapy (RAIT) is a highly effective therapy for thyroid cancer and is usually general in patients with various thyroid diseases. Safety is considered an essential plan in treating patients suffering from cancer with iodine-131. Aim of the study: was to evaluate the effect of nursing guidelines on safety measures awareness among patients with thyroid disorders undergoing Radioactive Iodine Therapy.  Study design: A quasi-experiment study design was used to achieve aim of the study. Setting: The outpatient clinics of the Nuclear Medicine Center for radioactive iodine therapy at Ain Shams University Hospital. Cairo. Egypt. Sample: A Purposive sample of 50 patients was participated in the current study. Tools: Data were collected using three tools as follows: Tool1: Patient Interview Questionnaire (pre/post and follow up). Tool 2. Swallowing exercise observational checklist (pre/post and follow up), and Tool 3- Complications assessment tool (pre/post and follow up).  Results: there was significant improvement in patient`s  knowledge, awareness regarding the safety measures of RAIT, patient`s practice of swallowing exercises and significant decreasing in occurrence of short and long term complications after nursing guidelines implementation. Conclusion: It was concluded that nursing guidelines have a positive effect in increasing patient`s knowledge, patient`s awareness of safety measures, swallowing exercises practice, and reducing the incidence of treatment complications. Recommendation: Continuous educational guidelines should be constructed and implemented about safety measures to the patients with thyroid diseases and receiving RAIT.