A case of hyperthyroid disease after total thyroidectomy is reported. An initial scintigraph with Tc-99m sodium pertechnetate confirmed the absence of uptake in the neck. The view of the pelvis revealed a rounded area of increased uptake on the left, near the sacroiliac joint (results of bone scintigraphy were negative). A wholebody scan with iodine-131 confirmed a struma ovarii that was bilateral, which occurs in 5% to 10% of patients with this condition.