Silent thyroiditis, excluding postpartum thyroiditis and destructive amiodarone thyroiditis, is a relatively uncommon cause of thyrotoxicosis and recurrent cases are even rarer. We present four patients with recurrent silent thyroiditis. The number of episodes ranged from two to nine. All four patients had episodes that were similar in duration (4-6 weeks) as well as in their clinical (no viral prodrome or neck pain), biochemical (high total triiodothyronine [T(3)], free thyroxine [T(4)], and low thyrotropin [TSH] presence of antibodies to thyroid antigens), and scintigraphic (low radioiodine uptake) findings. Individual symptoms and symptom-free duration (from 1 to 4 years) were more variable. No associations were found with regard to medications, pregnancies, or other disease states previously implicated in thyroiditis. One patient was unsuccessfully prescribed thyroid hormone to prevent recurrence. Three were treated with radioablative iodine therapy during the recovery phase of an episode; they became hypothyroid and take replacement l-thyroxine. They have remained symptom free.