In this study, the effects of impregnation materials di-ammonium phosphate, aluminium sulphate, potassium carbonate, calcium chloride, zinc chloride on combustion properties of 3 ply laminated veneer lumbers (LVL) produced from Walnut (Juglans regia L.) using phenol formaldehyde (PF), poly (vinyl acetate) have been investigated. The pressure-vacuum method was used for impregnation process. Combustion test was performed according to the procedure of ASTM-E 69 standards. During the test, mass reduction, temperature and released gas (CO, NO(x), SO(2), O(2)) were determined every 30s. As a result, zinc chloride was found to be the most successful fire-retardant chemical in LVL at PF adhesive. Since it diminishes combustion, the fire retardant of LVL produced from walnut using PF adhesive can be advised. Copyright (C) 2009 John Wiley & Sons, Ltd.