The thyroid gland is an endocrine gland with high vascularise. It is formed of right and left two side lobes and of isthmus lobe joining the two lobes and this resemble the letter H. Morphological variation and developmental abnormalities of the thyroid gland has been reported in the literature in a wide range. In our report, total thyroidectomy was performed to a 30 year old woman. During the operation it was seen that the right and left thyroid lobe was independent from each other and isthmus lobe was absent. We will present a case of thyroid isthmus agenesis and discuss the clinical importance and the incidence of this case.