This study evaluated decay and termite resistance of plyvvood panels treated \vith didecyl dimethyl ammonium tetrafluoroborate (DBF) and didecyl dimethyl ammonium chloride (DDAC) as quaternary ammonia compounds. Meclıanical properties and bonding quality of treated plyvvood specimens were also tested. The modulus of rupture (MOR) values of botlı DBF- and DDAC-treated plyvvood specimens fulfılled minimum requirements for plyvvood F25-F30 (38-45 N/mm2) set by the EN standards. The modulus of elasticity (MOE) of DDAC-treated plyvvood specimens decreased vvhen compared vvith DBF-treated and untreated plyvvood specimens. The bonding quality values of ali specimens did not meet the requirements set by the TS standards. The results suggest that DBF and DDAC may decrease meclıanical properties by possible interaction vvith the glue and vvood components depending on botlı clıemical structure and retention levels in treated plyvvood specimens. Decay resistance tests shovved that DBF-treated plyvvood specimens vvere more resistant against the fungi tested vvhen compared vvith those of DDAC treated; hovvever, both DBF and DDAC had no protective effect against termite attack.