We highlight a case of disabling myopathy following radioablative iodine treatment for follicular carcinoma of the thyroid. A 34-year-old man presented with a tender neck swelling, ultrasound and biopsy were suggestive of thyroid malignancy. Thyroidectomy was undertaken and histology confirmed follicular carcinoma of the thyroid. Treatment with ablative radioiodine followed and within days the patient developed disabling myopathy. Investigations to date do not reveal any other cause for the myopathy and there is no evidence to suggest that this is a paraneoplastic phenomenon. We believe this is the first reported case of ablative radioiodine-induced mypoathy.