Riedel's thyroiditis is a rare fibro-inflammatory process originating in the thyroid gland with progressive extension and invasion of surrounding tissues. Patients frequently present with a stony hard thyroid mass suggestive of anaplastic carcinoma. We report a striking case of Riedel's thyroiditis associated with hypothyroidism, hypoparathyroidism and bilateral vocal cord paralysis. A dramatic response to high dose prednisone and levothyroxine therapy was seen, with recovery of parathyroid and vocal cord function. Our case suggests that early initiation of combination therapy may be important, particularly in the presence of severe disease.