When impregnated wood is used for outdoor applications, it is essential that the active ingredients do not leach from it. Therefore, the evaluation of fixation of active ingredients is an important part of the development of wood preservatives. For this purpose, numerous standard and non-standard methods are utilized. 3 standard methods: ENV 1250-2, EN 84 and OECD Recommendation were used, and applied on spruce wood impregnated with 4 products: water solution of boric acid, a combination of boric acid and montan wax water emulsion, an aqueous solution of copper (II) sulphate and copper-ethanolamine (commercial solution (Silvanolin). Apart from the leaching method utilized, leaching of boron from boric acid treated wood was the most prominent, and on the other hand copper at Silvanolin treated wood exhibited the best performance. The least aggressive leaching method is OECD method, however, the most aggressive is EN 84 one.