Abstract. Sodium iopodate has recently been advocated for long-term control of hyperthyroidism in Graves' disease. Its advantages over conventional therapy are a rapid fall in thyroid hormones and control of symptoms with a simple dosage regime. We report a case in which severe resistant hyperthyroidism developed during treatment of Graves' disease with sodium iopodate. Sodium iopodate may not be suitable for long-term use in all patients with Graves' disease.