Accessory cervical thymic tissue has been rarely reported. However, it should be included in the differential diagnosis of neck masses in children, along with branchial anomalies, lymph nodes and other tumors. This lesion occurs along the descending line of the thymus between the angle of mandible and superior mediastinum. A 2-month-old infant presented with an asymptomatic left sided neck mass. MRI revealed a well defined homogeneous mass in the deep lobe of left parotid gland. At operation, an easily identified soft tissue mass was found in the left submandibular area, measuring $3{ imes}1.5cm$. It was completely excised. Microscopic examination revealed normal thymic tissue.