TAGHIYARI HR. 2012. Correlation between gas and liquid permeability in some nanosilver-impregnated and untreated hardwood. Permeability is an important physical property of wood as a porous material that determines many of its applications. The present study was therefore aimed at analysing the effects of nanosilver impregnation on specific longitudinal gas permeability as well as two longitudinal liquid permeability, i.e. first drop time and 5-cm lowering time using Rilem tube test method. Relationship between these permeability times were analysed in three native solid wood, Populus nigra (poplar), Fagus orientalis (beech) and Carpinus betulus (hornbeam). Specific longitudinal gas permeability values obtained were 20.77 × 10-13, 8.20 × 10-13, 7.85 × 10-13 and 6.10 × 10-13 m3 m-1 in poplar, beech, hornbeam sapwood and hornbeam heartwood respectively. Empty-cell impregnation process of nanosilver suspension not only washed out part of the extractives but also the pressure might have removed some of the tiny physical tissues and natural obstacles in vessel elements. Consequently, permeability increased by more than 50% in poplar and hornbeam heartwood which had simple perforation plates. However, permeability was decreased by 3.7% in beech. We hypothesised that this was due to first, the settlement of nanosilver particles or extractives that were dissolved in the suspension within scalariform perforation plates, thus, blocking fluid transfer process; and second, collapsing and accumulation of the scalariform perforation plates due to the high pressure in impregnation vessel. Clear direct relation was found between gas and liquid permeabilitiy.