In 1971, Costello described a new syndrome in 2 patients. The major clinical findings comprise short stature; redundant skin of the neck, palms, soles, and fingers; curly hair; relative macrocephaly; depressed nasal bridge; papillomata around the mouth and nares; distinct facial gestalt; hyperextensible joints; and mental retardation. We present a third patient and review the manifestations of this condition.