Thyroid hemiagenesis is a very rare abnormality, in which one thyroid lobe fails to develop. Most of the patients diagnosed have an associated thyroidal disease. The true prevalence of thyroid hemiagenesis is not known, but it is estimated to be 0.02% in normal children. We report a forty-five year-old female patient with a multinodular goiter in left lobe, associated with hemiagenesis of right lobe and isthmus.