Thyroid hemiagenesis can be associated with various thyroid pathologies such as papillary thyroid cancer or nodular goiter. However, we did not encounter any publication in the literature in which hemiagenesis could be observed together with retrosternal goiter. In this report, a thyroid hemiagenesis associated with a benign nodular goiter extending retrosternally is reported. A 59-year-old male patient presented to the surgery clinic because of swelling in the neck. A mass was observed in the right thyroid lobe extending to the retrosternal region. On ultrasonography, a nodule in the right thyroid lobe measuring 63 mm was determined, which was extended retrosternally. However, the left lobe of the thyroid could not be visualized. Scintigraphy and Computerized Tomography confirmed hemiagenesis. Total thyroidectomy was performed without sternotomy. In conclusion, thyroid hemiagenesis can be associated with a retrosternally located nodular goiter