Objective: The objective of this case report was to highlight the importance of isolating the thyroid as the source of infection in toxic-appearing patients with preexistent thyroid nodules who present with neck pain.Methods: The clinical presentation, evaluation, laboratory results, imaging findings, and management of a patient with acute suppurative Haemophilus influenzae thyroiditis are presented.Results: A 55-year-old female with known nodular goiter presented with an acute increase in the size of her thyroid, neck pain, fever, and symptoms of hyperthyroidism. Laboratory studies were remarkable for leukocytosis, elevated inflammatory markers, and elevated free thyroid hormones. A computed tomography scan of the neck showed possible areas of abscess formation in the left thyroid lobe, and a radioactive iodine uptake showed a diffuse uptake of 0.9% at 5 hours and 0.5% at 24 hours. Blood cultures and culture from a left thyroid nodule aspirate grew H. influenzae. Initial management included broad-spectrum antibiotics and beta-blockers. Given the lack of clinical improvement, a left hemithyroidectomy was performed. Pathologic examination demonstrated an extensively infarcted adenomatoid nodule with abscess formation. There were no procedural complications, and the patient was discharged in stable condition.Conclusion: Suppurative thyroiditis is an uncommon but potentially serious disorder. This condition should be considered in any patient with known thyroid abnormalities who presents with neck pain. Early diagnosis is vital to guide the proper antimicrobial therapy and the required surgical interventions. With appropriate management, the prognosis is usually excellent. (AACE Clinical Case Rep. 2017;3:e251-e254) Abbreviation: FNA = fine-needle aspiration