For certain families of real symmetric spaces (G/H i ) i = 1 , , r , where each G/H i can be realized as a connected component of the complementary set of an irreducible hypersurface, we construct a Zeta function which is associated to representations of the H i -spherical principal series of G, and we prove its functional equation. These families of symmetric spaces are the open orbits of the real prehomogeneous vector spaces of commutative parabolic type, or in an equivalent language, those coming from the real simple Jordan algebras.Pour certaines familles d'espaces symetriques reels (G/H i ) i = 1 , , r , ou chaque (G/H i ) est realise comme une composante connexe du complementaire d'une hypersurface, nous construisons une fonction zeta associee aux representations de la serie principale H i -spherique de G, et nous montrons son equation fonctionnelle. Les familles d'espaces symetriques considerees correspondent aux orbites ouvertes des espaces prehomogenes reels de type parabolique commutatifs, ou encore, dans un langage equivalent, des algebres de Jordan simples reelles.