Thyroid hemiagenesis is a rare congenital anomaly in which one lobe of thyroid fails to develop; which may or may not be associated with failure of development of the isthmus. Most of the patients remain asymptomatic. Thyroid pathologies are more common in these patients than the normal population. Euthyroid cases without any above mentioned disorders need reassurance for the patient. Importance of this case lies in two important things. First thyroid hemiagenesis is associated with increased incidence of other associated disorders including malignancy. Hence close follow up is essential. Secondly, when in euthyroid status, proper patient counselling and avoidance of unnecessary surgery are of paramount importance to avoid permanent hypothyroidism.