Abstract: Objective To investigate the changes in ^99mTc and ¹³¹I uptake in patients with Grave’s disease after intake of iodine-containing food.Methods The 3-hour and 24-hour radioactive iodine uptake (RAIU) and ^99mTc uptake ratio (TI) were measured and the thyroid weight (TW) was estimated in 20 patients with Graves’ disease both before and after restraint of iodine-containing diet.Results Significant difference was found in RAIU and TI in patients after restraint of iodine-rich diet (Z=3.920, P=0.000 for 3-hour RAIU and Z=3.920, P=0.000 for 24-hour RAIU; Z=2.199, P=0.028 for TI and Z=3.920, P=0.000 for TW estimated from ^99mTc images). The tendency in such changes was significantly different (Z=4.066, P=0.000 for RAIU and TI; Z=4.243, P=0.000 for RAIU and TW). After restraint of iodine-rich food, RAIU of 3-hour and 24-hour increased in all the patients, and TI decreased in 16, remained the same level in 2 and increased in 2 patients; TW decreased in 18 and increased in 2 patients.Conclusion Iodine-containing food has different effects on thyroid ¹³¹I and ^99mTc uptakes, which decreases ¹³¹I uptake in all the patients and increases ^99mTc in 90% of them.