Failure of embryologic development of a lobe of the thyroid gland is a rare anomaly. Usually, this condition is diagnosed when there are some other pathologic conditions in the gland and is often found when a patient presents with a thyroid nodule, which in reality is compensatory hypertrophy of the side that is present, therefore appearing as a nodule. A variety of pathological conditions occur in the remaining thyroid tissue in association with this rare anomaly such as adenoma, carcinoma, subacute thyroiditis, colloid nodule, Graves' disease, simple goiter, and Hashimoto thyroiditis. Association of Graves' disease with ophthalmopathy and thyroid hemiagenesis is quite rare and very few cases are reported in the literature. We report a 29-year-old female presented as Graves' disease and Graves' ophthalmopathy with left lobe hemiagenesis of the thyroid gland.