Persistence of the thymus gland in the neck is extremely rare. The usual case reported is that of a hypertrophied thymus in its normal position in the mediastinum, with a portion projecting upward into the root of the neck.* Two instances of thymic cyst have been found in the neck.† Microscopic rests of thymic tissue in or near the parathyroid glands have been identified and are explained as the result of development from contiguous embryological anlage.‡ In the following case, a tumor of the neck was removed and was found to be morphologically identical with the thymus. We have not been able to find a similar case recorded. REPORT OF CASE A 3½-year-old white boy was admitted to the Barnert Memorial Hospital on June 23, 1954. His mother had first noticed a small lump in the left side of his neck about 18 months previously. The lump had gradually increased