: Langerhans cell histiocytosis (LCH) in adults is a rare disorder of unknown etiology characterized by monoclonal proliferation of Langerhans cells. It belongs to dendritic cell disorders and occurs in 1-2 adults per million. The most common endocrine manifestation of classical LCH is associated with the posterior pituitary, with clinical symptoms of diabetes insipidus. Less than 80 reported cases of LCH involving the thyroid gland have been published so far. We present the case of a 39 years old woman with 10 years history of diabetes insipidus and secondary amenorrhoea, which appeared after second delivery. She was suspected for lymphocytic inflammation of pituitary and she was administered steroid treatment. She was also treated symptomatically with desmopressin, L-thyroxine, estrogen and progestagen replacement therapy due to diabetes insipidus, secondary hypothyroidism and hypogonadotropic hypogonadism. In September 2014, she noticed a painless, firm tumour of the neck. Ultrasound (US) examination demonstrated bilateral, solid, hypoechogenic thyroid nodules. The result of fine-needle aspiration biopsy (FNAB) was not diagnostic. Due to rapid progression and US image of the tumour, she was referred for surgery. In postoperative histopathology tumour cells were positive for CD1a and S-100 protein, therefore diagnosis of LCH was established. Postoperatively, the results of thoracic computed tomography scan, abdominal US and bone scintigraphy revealed no evidence of multifocal disease. We have not observed any disease recurrence in the patient after a year of follow-up in postoperative course. This case illustrates diagnostic and therapeutic difficulties in patient with LCH.