Congenital smooth musele hamartomas appear at birth as hypertrichotic patches or plaques with or without hyperpigmentation. Histologic characteristic is hyperplasia of dermal smooth muscle bundles. We report a case of congenital smooth muscle harnartoma in 5-year-old female, who showed localized excessive-hairy, skin-colored patch on the lateral surface of left. elbow, which were found at birth. Biopsy specimen showed hyperpigmentation of the basal layers of epidermis, melanophages in upper dermis, and hyperplasia of smooth muscle bundles in lower dermis.