We prove that a Kleinian surface groups is determined, up to conjugacy in the isometry group of H 3 , by its simple marked length spectrum. As a first application, we show that a discrete faithful representation of the fundamental group of a compact, acylindrical, hyperblizable 3-manifold M is similarly determined by the translation lengths of images of elements of π1(M ) represented by simple curves on the boundary of M . As a second application, we show the group of diffeomorphisms of quasifuchsian space which preserve the renormalized pressure intersection is generated by the (extended) mapping class group and complex conjugation.