A case of sight threatening thyroid eye disease (TED), arising in a 55 year old woman with primary hypothyroidism due to Hashimoto’s thyroiditis (HT), is described. TSH receptor antibody (TSHRab) was positive as were orbital antibodies. Initial management consisted of methylprednisone intravenously followed by prednisone orally in a tapering dose, orbital irradiation and decompressive surgery. Visual acuity improved but 9 months later, there was evidence of relapse with features of compressive optic neuropathy, and exophthalmos had worsened. Prednisone dose was increased. At that time, TSHRab was negative. She underwent total thyroidectomy on the understanding that this was experimental therapy, surgery confirmed that thyroid pathology was solely TH without any evidence of Graves’ disease. Prednisone was successively tapered without further relapse. Rehabilitative ocular muscle surgery is planned. Whether the improvement seen in TED can be attributed to effect of removal of thyroid antigens following thyroidectomy is purely speculative. Our case illustrates that relapsing sight threatening TED is part of spectrum of TED in HT and demonstrates that clinical features can be severe.