Copper based wood preservative solutions are excellent fungicides, but unfortunately they do not fix well in wood: therefore, they are prone to leaching. Chromium compounds enable copper fixation, but their use is not desired due to potential chromium carcinogenic effect. One of the environmentally acceptable alternatives for copper fixation is combination of ethanolamine and octanoic acid. Wood preservatives on the basis of copper, ethanolamine and octanoic acid are sufficiently fixed in wood, but there are no data available on minimum effective concentration. Therefore, wood preservative on the basis of copper(II) sulphate, ethanolamine, octanoic acid, boron and quaternary ammonium compound of 3 different concentrations were used (cCu= 1, 0.75 in 0.5 %) for vacuum impregnation of Norway spruce specimens (Picea abies). Impregnated specimens were conditioned for 4 weeks, followed by leaching of half of the specimens, according to the EN 84 procedure. Afterward specimens were exposed to wood decay fungi (Coniophora puteana, Antrodia vaillantii, Serpula lacrymans, Trametes versicolor and Gloeophyllum trabeum) according to the EN 113 procedure. After 16 weeks of exposure, their mass losses were determined gravimetrically. Results show that the tested wood preservative solution exhibited sufficient protection against the tested wood decay fungi at leached and unleached specimens at all 3 concentrations. Spruce impregnated with the developed copper-ethanolamine wood preservative was protected even against copper tolerant fungal strains of Antrodia vaillantii.