Thyroid hemiagenesis is rare congenital anomaly that one lobe of thyroid fails to develop. It is often asymptomatic and discovered incidentally with other thyroid disease such as hypothyroidism, hyperthyroidism, multinodular goiter, benign adenoma and cancer. Most cases reported are left thyroid lobe agenesis and occurred in female. Compensatory hypertrophy occurs in most cases. Many cases are asymptomatic and detected incidentally, so awareness of its existence can help its detection and proper treatment. Here, we report a case of thyroid hemiagenesis accompanying hypothyroidism with a review of literature.