Langerhans cell granulomatosis(LCG), previously termed 'Histiocytosis-X', is one of the rare disease. LCG is characterized by proliferation of Langerhans cells in a unifocal or multifocal pattern. And LCG may be manifested in a variety of way, ranging from a spontaneously regressing solitary lesion to a multisystem life-threatening disorder. This disease usually involves the bone, lung, skin and lymph node. The most common endocrinologic abnormalities in LCG are diabetes insipidus and growth hormone deficiency. LCG involving the thyroid gland is extremely rare and only a small numbers of cases have been reported worldwide. A 41-year-old diabetic female visited the hospital due to the neck swelling for 3 months and she also complained of polyuria, polydipsia and easy fatigue. LCG involving multiple organs included thyroid gland was diagnosed by high-resolution CT of lung, by characteristic histological findings of the thyroid lesion and by the immunohistochemical staining for S-100 protein and OKT 6(CD la). She is followed at OPD without any medication.