Abstract: Disclosed are panels of medium density fibreboard (MDF). The panels comprise wood fibres, the largest dimension of which is 7 mm or below, pressed together with an adhesive. The panels are of a large and thin type, having an aspect ratio of at least 100 and a surface area of at least 1 m2. Typical problems associated with such large and thin panels, e.g. warping behaviour, are addressed by employing wood fibres are made of acetylated wood.