Brown tumor is a giant cell lesion associated with hyperparathyroidism. It is a non-neoplastic condition and represents terminal stage of the remodeling process in hyperparathyroid state. We report a case of brown tumor with multiple lesions in craniofacial region associated with ectopic parathyroid adenoma revealed after acute L-thyroxine poisoning. This case report emphasizes on the need for routine biochemical investigations along with serum calcium, phosphorus and parathyroid hormone levels in patients on thyroxine therapy.