Let G = (V. E) be a connected graph such that edges and vertices are weighted by nonnegative reals. Let p be a positive integer. The minimax subtree cover problem (MSC) asks to find a pair (X, F) of a partition X = {X-1, X-2,....X-p} of V and a set F of p subtrees T-1, T-2,..., T-p, each T-i containing X-i so as to minimize the maximum Cost of the subtrees, where the cost of T-i is defined to be the sum of the weights of edges in T-i and the weights of vertices in Xi. In this paper. we propose an O(p(2)n) time (4 - 4/(p + 1))-approximation algorithm for the MSC when G is a cactus. (c) 2006 Elsevier B.V. All rights reserved.