Bambusi D., Gaeta G. Existence of invariant tori for non hamiltonian perturbations of integrable systems (12K, Plain TeX) ABSTRACT. We extend known results on the existence of invariant tori for non hamiltonian perturbations of integrable systems, to the case where the unperturbed system is anisocronus. The result holds for perturbations admitting a definite finite number of derivatives, and belonging to a generic class.