Trichothiodystrophy is a rare autosomal recessive disorder and it is caused by reduced levels of high-sulfur amino acids and most particularly cystine in hair shafts. The patients with trichothiodystrophy show a broad range of clinical phenotypes from only hair involvement to multisystem abnormalities. A 7-year-old girl visited the clinic with a complaint of short, sparse and slow-growing hair, which had been presented since birth. The patient`s hair showed characteristic dark and light banding, which gave a "tiger tail" appearance under light microscopy, and polarization and cuticular degeneration were seen under the scanning microscopy. Evaluation of the mineral density in the patient`s hair shaft showed a low level of sulfur. We herein report on a case of trichothiodystrophy with sulfur-deficiency in the hair shafts. (Korean J Dermatol 2011;49(1):36~39)