Sapwood samples of <i>Pinus radiata, Populus robusta, and <i>Eucalvptus regnans were treated with various solution strengths of a) alkyl dimethyl benzyl ammonium chloride and b) copper-chrome-arsenate wood preservative. The treated samples were exposed to attack by pure cultures of both basidiomycete and soft-rot fungi. The quaternary ammonium compound was slightly less effective than CCA in preventing decay by basidiomycetes, but was superior in preventing soft-rot attack. -- AATA