Black hairy tongue is the name given to the appearance of an abnormal coating of the tongue and occurs in adults. It is the result of hyperkeratosis of the filiform lingual papillae which, on gross examination appear hair-like with a variable tinctorial aspect from yellow-brown to black. The pathogenesis is unknown. A number of etiologic factors have been implicated including the administration of topical or systemic antibiotics, poor hygiene, smoking, alcohol and the use of mouthwashes. We report a case of black hairy tongue that may be associated with oral administration of minocycline. (Korean J Dermatol 2002;40(3): 319~321)