[en] Radioactive iodine (RAI) ablation following thyroidectomy is recommended for most patients diagnosed with papillary and follicular thyroid carcinoma. We performed a literature search on MEDLlNE and EMBASE, using keywords, such as, differentiated thyroid carcinoma, radioiodine therapy, "1"3"1I complications, adverse effects and side effects, and chose the most relevant studies till date to prepare this work on the side effects of RAIT (Radioactive Iodine Therapy) for thyroid cancer. We contacted authors of published studies where appropriate for further information. Also, the percentage incidence of the hazards was determined for North Indian population accessing data from Govt. Medical Colleges of Punjab, Haryana, and Postgraduate Institute of Medical Education and Research, Chandigarh. The most prominent side effect came out to be xerostomia with an incidence of 47%, followed by local neck pain and swelling (39%). The incidence of gastritis was also common (34%). Radioactive iodine therapy complications have been divided into early and late effects. Early complications include gastrointestinal symptoms, radiation thyroiditis, sialadenitis/xerostomia, bone marrow suppression, gonadal damage, dry eye, and nasolacrimal duct obstruction. Late complications include secondary cancers, pulmonary fibrosis, permanent bone marrow suppression, and genetic effects. As "1"3"1I is an efficacious form of treatment that can significantly decrease the rate of mortality, recurrence and metastasis, and as the side effects are often minor and well-tolerated, radio iodine therapy remains the principal mode of treatment for patients. (author)