Southern pine samples were treated with disodium octaborate tetrahydrate or a boric acid/borax mixture alone or in combination with an acrylic polymer system containing a water repellent. Treated material was subjected to decay tests with white- and brown-rot basidiomycetes and to decay and soil depletion studies in an unsterile soil-bed system. Polymer treatment alone or in combination with borates substantially reduced decay by all the fungi tested. The mechanism of action of the polymer was not associated with reduction in leaching or soil depletion of borates, and several alternative mechanisms are considered. The use of such polymers in the development of wood preservative formulations is discussed