Medium Density Fibreboard (MDF) is a reconstituted wood panel product. It is a dry-processed fibreboard manufactured from wood fibres, as opposed to veneers or particles, and is denser than plywood and particleboard. MDF has an even density throughout and is smooth on both sides.

MDF is reconstituted into wood sheets in a variety of widths and lengths. Bonding is achieved by the addition of synthetic resin adhesives, which are cured under heat and pressure. Paraffin wax is added to assist with water repellency, while other chemicals can be added during manufacturing for more specific protection.