The linear programing algorithms available for optimizing the routing of shipments in multi-plant, multi-destination systems cannot, in the current state of knowledge, be applied directly to the more general problem of determining the number and location of regional warehouses in large-scale distribution networks. This paper outlines a heuristic computer program for locating warehouses and compares it with recently published efforts at solving the problem either by means of simulation or as a variant of linear programing. The heuristic approach outlined in this paper appears to offer significant advantages in the solution of this class of problems in that it 1 provides considerable flexibility in the specification modeling of the problem to be solved, 2 can be used to study large-scale problems, that is, complexes with several hundred potential warehouse sites and several thousand shipment destinations, and 3 is economical of computer time. The results obtained in applying the program to small scale problems have been equal to or better than those provided by the alternative methods considered.