The problem considered in this paper consists in defining an assignment of frequencies to radio links, to be established between base stations and mobile transmitters, which minimizes the global interference over a given region. This problem is NP-hard and few results have been reported on techniques for solving it to optimality. We have applied to this version of the frequency assignment problem an ANTS metaheuristic, that is an approach following the ACO optimization paradigm. Computational results, obtained on a number of standard problem instances, testify the effectiveness of the proposed approach.