Protective preparations on copper based compounds are often use for protection of wood. Copper based preparations are very efficient fungicides, however, Cu from wood leaches out. Recently, tolerant strains of fungi have appeared, against which copper based preservatives are not efficient any more. That is why we tried to find out the influence of quaternary ammonium compounds on leaching of copper based fungicides. Samples from Norway spruce wood were vacuum impregnated with preparations based on copper, ethanolamine, quaternary ammonium compound, octanoic acid and biocide topbor. After drying and leaching we determined concentration of copper in the leachate by atomic absorption spectroscopy. It was found out, that leaching of copper was strongly reduced by the presence of amines. Fungicidal properties of the impregnated samples were determined by the mini block test method. The leached and non-leached samples were exposed to Gloeophyllum trabeum, Antrodia vaillantii and Trametes versicolor. It was found out that leaching did not decrease resistance against wood decay fungi.