Thymoma is one of the most common neoplasms of the mediastinum, and the most frequent tumor of theanterosuperior compartment. Thymoma developing from arrested undescended thymic cells in the neck is, however,rare. The most common extrathoracic location is the vicinity of the thyroid. Two cases of aberrant cervicalthymoma are presented. Both manifested as mass lesions at the thoracic inlet, with superior displacement of thethyroid. The masses had clinical features similar to those previously reported for cervical thymoma: preponderancein women, and the absence of myasthenic symptoms, but in one case there was malignant transformation.