A 51-year-old Japanese male had been maintaining hemodialysis for 20 years. He had advanced secondary hyperparathyroidism. He had total parathyroidectomy (PTX) and autotransplantation in 2003. After the operation, clinical and endocrinologic findings showed transient thyrotoxicosis. There was no immunologic finding compatible with Graves' disease and chronic thyroiditis. After PTX, radioisotope accumulation markedly decreased on 99m TcO 4 − thyroid gland scintigram and blood flow diminished on thyroid gland ultrasonogram. These findings absolutely recovered with the resolution of thyrotoxicosis within 1 month. It appears that disturbance of the microcirculation in the thyroid gland by manipulation during operation might be a cause of transient thyrotoxicosis after PTX. It is important to consider transient thyrotoxicosis as a complication of PTX in secondary hyperparathyroidism.