The incubation of wood fibres with a phenoloxidase (laccase) results in the oxidation of the lignin crust on the fibre surface which finally is released from the fibre surface into the incubation medium. During this reaction, the lignin is highly oxidized, as can be seen from its high carboxyl content. When fibres treated with the enzyme are pressed together under conditions usually employed during the process of making fibre boards, boards are obtained which meet the required standards for German medium density fibre board (MDF). The enzymatically activated fibres in the wood composites made by this process are bound together in a way which is closer to the situation in the naturally grown wood than any other process used today in the present production of wood composites.