Introduction: Goiter is abnormal growth of the thyroid gland. When goiter extends into the mediastinum it is called retrosternal or substernal. Substernal goiter can cause compression of the great vessels, trachea, and esophagus. When it compresses trachea it can result in airway obstruction. In that case treatment of choice is thyroidectomy and Radio Iodine Ablation (RIA). But some patients are considered to be high risk for operation due to multiple comorbidities. We are presenting this case where we tried experimental therapy with airway stent and external beam radiation. Case: An 81 year old female presented to the hospital complaining of chest pain. She also reported dysphagia to solids and liquids and weight loss during one month. Past medical history included congestive heart failure, atrial fibrillation, chronic obstructive pulmonary disease with home oxygen support. On physical exam thyroid was palpable to the level of sternal notch. Arterial blood gases showed hypoxemia (PO2 63), thyroid function tests showed an abnormally suppressed TSH (<0.005 IU/ml), elevated free T4 (2.48 ng/dl) and normal T3. Thyroid stimulating immunoglobulin, IgG, IgM and IgA levels were normal. Thyroglobulin and thyroid peroxidase antibodies were negative. Chest X-ray revealed an upper mediastinal mass. Chest CTA showed a very large substernal goiter with left thyroid lobe of 7.4 x 3.4 x 7.8 cm that extended to the level of the carina causing compression of the upper to mid trachea and of the upper esophagus. The smallest diameter of the trachea was 6 millimeters. Ultrasound revealed an enlarged heterogeneous thyroid with a solid lesion in the left side inferiorly. Due to administration of IV contrast for the CTA, iodine uptake scan was not performed. Patient was determined to be of high surgical risk due to her comorbidities and she did not consent for thyroidectomy. She was treated with methimazole 20mg daily and IV hydrocortisone 50mg TID. Due to the administration of IV contrast she was not candidate for RIA either. Short term beam radiation was started. For the acute relief of respiratory distress the lesion was transversed through flexible bronchoscopy and a 16 mm by 80 mm covered ultraflex tracheobronchial stent was placed in the trachea. The post-stent lumen size was 80% of normal. Patient’s respiratory status improved and the treatments with external beam radiation were continued. Conclusion: The treatment of choice for substernal goiter that causes airway obstruction is surgery. RIA can be an alternative when surgery is contraindicated. Since surgery as well as RIA was not an option for this patient we attempted external beam radiation to reduce the size of goiter. Because this treatment takes several weeks to be effective, temporary airway opening via an airway stent is the option for acute relief of symptoms.