We report a case of plexiform neurofibroma developed under the overlying speckled lentiginous nevus, which occurred in a 20 year-old man. In this patient and his family no other signs of von Recklinghausens disease were found. Discussion is focussed on the fact that both plexiform neurofibroma and speckled lentigmous nevus, which represent a defect in the neural crest, occurred in the same area of the skin.