Abstract. Let Φ be a system of ideals on a commutative Noetherian ring R, and let S be a multiplicatively closed subset of R. The first result shows that the topologies defined by {I a } I∈Φ and {S(I a )} I∈Φ are equivalent if and only if S is disjoint from the quintasymptotic primes of Φ. Also, by using the generalized Lichtenbaum-Hartshorne vanishing theorem we show that, if (R, m) is a d-dimensional local quasi-unmixed ring, then H d Φ (R), the dth local cohomology module of R with respect to Φ, vanishes if and only if there exists a multiplicatively closed subset S of R such that S ∩ m = ∅ and the S(Φ)-topology is finer than the Φ a -topology.1. Introduction. Throughout this paper, all rings considered will be commutative and Noetherian and will have non-zero identity elements. Such a ring will be denoted by R and a typical ideal of R will be denoted by I. Let (Λ, ≤) be a (non-empty) directed partially ordered set. A system of ideals of R over Λ is an inverse family Φ = {I α : α ∈ Λ} of ideals of R with the additional property that, for all α, γ ∈ Λ, there exists δ ∈ Λ such that I δ ⊆ I α I γ . Systems of ideals are a very useful generalization of the sets of powers of an ideal I in a ring R, and there are many important systems of ideals that are not powers. They have played an important role in many research papers, and there are numerous results concerning them in the literature (e.g., see [2], [3] and [7]).Let Φ denote a system of ideals (of R) and S a multiplicatively closed subset of R. For an ideal I of R, the S-component of I, denoted by S(I), is defined to be the union of (I : R s), where s varies in S. The integral closure of I in R is the ideal