Thalidomide is highly effective against multiple myeloma, but some patients must discontinue this medication due to adverse effects. We present herein an instructive case report on thalidomide-associated hypothyroidism in a patient with multiple myeloma. Thyroid hormone replacement therapy allowed us to restart administration of thalidomide, a potentially life-saving therapy. Known adverse effects of thalidomide, such as lethargy, constipation, and bradycardia, are potential symptoms of hypothyroidism, but we tend to overlook drug-associated hypothyroidism. Our case highlights the importance of routinely testing thyroid function in patients receiving thalidomide therapy.