The Tajuña (from the Latin Tagonius) is a river in central Spain, flowing through the provinces of Guadalajara and Madrid. It is a tributary of the river Jarama which in turn is a tributary of the Tagus. It rises in the Sierra de Solorio, near the town of Maranchón (Guadalajara), at a location known as Fuente del Carro near the village of Clares.