Abstract. Let G be a connected semisimple Lie group such that the associated symmetric space X is Hermitian and let Γ g be the fundamental group of a compact orientable surface of genus g ≥ 2.We survey the study of maximal representations of Γ g into G, that is the subset of Hom(Γ g , G) characterized by the maximality of the Toledo invariant ([17] and [15]). Then we concentrate on the particular case G = Sp(2n, R), and we show that if ρ is any maximal representation then the image ρ(Γ g ) is a discrete, faithful realizations of Γ g as a Kleinian group of complex motions in X with an associated Anosov system, and whose limit set in an appropriate compactification of X is a rectifiable circle.