This study investigated the relationship between panel density and dimensional stability properties of commercial manufactured medium and high density fiberboards (MDF and HDF, respectively). Experiments were conducted using DIN EN 318 (2005) standard method to determine expansion and swelling properties of the MDF and HDF as a function of panel density. A significant relationship was found between panel density and dimensional stability of the panels. Our results showed that dimensional stability of MDF and HDF panels were adversely affected by panel density. The linear expansion/contraction and thickness swelling/shrinkage increased with increasing panel density, principally for densities above 850 kg/m(3). The thickness swelling and shrinkage values were higher than linear expansion and contraction values.