Ectopic hamartomatous thymoma is a rare benign tumor of the lower neck occurring in the male adult predominantly. The origin of this tumor has been debated, but it is now believed to arise from remnants of the cervical sinus of His from early development. They are composed of epithelial, adipocytic, and spindle cells in variable amounts. Recognition of ectopic harmatomatous thymoma is important and needs to be differentiated from high-grade sarcomas such as synovial sarcoma or glandular malignant peripheral nerve sheath tumor. We here report on a case of ectopic hamartomatous thymoma arising in the left lateral neck of 33-year-old male patient.