Stability of 20 important inland wood species to the action of the gamma radiation of the dose of 1500 kGy was investigated. A part of wood prisms of each species was irradiated with gamma-rays in a special appliance of PXM-gamma-20 (of the Soviet make) provided in the radiation source of *h60*sCo with the activity at the time of investigations amounting to 5000 Ci and the dose power of 3.6 kGy/hour. To determine possible effect of irradiation of wood of the species under study, the wood density was determined by the stereometric methods as well as its inbibition and swelling in water and hardness after Chalais-Meudon were estimated. It has been proved that imbibition and swelling of irradiated wood exhibits in the first phase of wetting a decreasing tendency. However, along with longer staying of samples in water, imbibition and swelling of the irradiated wood did not differ practically from imbibition and swelling of natural wood. On the other hand, hardness of the irradiated samples exhibited a distinct decreasing tendency.