A bioremediation system for creosote-treated wood is proposed, based on the detoxifying capability of Pleurotus ostreatus, a ligninolythic fungus. Non-sterilized chipped contaminated wood was mixed at various ratios with wheat straw on which Pleurotus mycelia was grown. At 1:2 initial ratio contaminated wood:wheat straw, chemical analyses demonstrated an almost complete degradation of creosote oil components after 44 days, also confirmed by a significant reduction of ecotoxicity. Lower ratios, i.e. higher amount of contaminated wood, lower system efficiency, although a better creosote degradation was obtained by a stepped up wood addition.