Radioactive iodine therapy using I-131 for hyperthyroidism has been used for more than 50 years, and generally considered safe and devoid of major side effects. Appropriate patient selection criteria and clinical judgement concerning patient preparation should be employed for its optimal use. It has not been possible to resolve the trade-off between efficient definite cure of hyperthyroidism and the high incidence of post-therapy hypothyroidism. The dose of the I-131 needed to maintain euthyroid state remains an area of uncertainity and debate. Early side effects are uncommon and readily managable. Other than the need for long-term monitoring and, in most cases, lifelong thyroid hormone treatment for late adverse consequences of this treatment remains only conjectural. We have reviewed general principles and recent advances in radioiodine treatment for Graves hyperthyroidism, specially regarding to several controversies.