A 27-year-old female presented to our hospital because of anterior chest pain and left cervical tumor. Her chest X-ray film showed bilateral swelling of the superior mediastinum, which was composed of multiple mediastinal masses with obliteration of adjacent mediastinal fat on chest CT film. A specimen obtained from a left cervical lymph node histologically showed granuloma formation with central caseous necrosis, and the diagnosis of cervicomediastinal tuberculous lymphadenitis was therefore made. Both cervical tumor and mediastinal masses decreased in size following antituberculous chemotherapy. Mediastinal tuberculous lymphadenitis in young adults is rare. It is difficult to differentiate this condition from other mediastinal tumors, although its CT findings are characteristic.