The purpose of this study was to improve some physical properties of particleboard using chitosan treatment. Particleboard is a main product for furniture industry and also used as a home decoration material in Turkey; however, it has a poor dimensional stability. In this study, wood particles, which were obtained from a commercial plant, were treated with chitosan acetate solutions (2% wt). Treated particles before the assembly also had extra high-heat treatment to convert insoluble chitosan acetate film over the particles to insoluble chitin. Different time intervals and temperature regimes were used in this experiment to select suitable temperature and time for chitosan acetate conversion to chitin. 6% liquid phenol-formaldehyde resin was used based upon oven-dry weight. The mat was pressed at 200 degrees C for 8 minutes to form 1.2 cm thick and a target of 0.66 g.cm(-3) density panel. Physical properties of the chitosan treated particleboards were improved; thickness swelling and water gain of the chitosan treated panels were reduced over untreated control panels after the 24-hour water-soak test. There was positive significant effect of chitosan treatments on internal bond strength.