Time course of thyroid function. The first thyrotoxicosis episode was misdiagnosed as Graves’ disease and rapidly changed to a hypothyroid state due to thiamazole administration. One and a half years later, a second thyrotoxicosis episode occurred, and the patient recovered without treatment. Four years after the first episode of thyrotoxicosis, the third thyrotoxicosis episode occurred. Low Tc-99 m uptake without fever and pain indicated painless thyroiditis. Retrospectively, all of these thyrotoxicosis episodes seemed to be repeated painless thyroiditis.