In this study, we tested printing materials from PLA thermoplastic with the addition of wood dust. We used filaments with a content of 10 %, 20 %, 30 %, 40 % and 50 % of wood dust based on the weight of filament. With 3D printer Zortrax M200 we printed 12 samples from each material, which were conditioned after drying and weighing in chambers with varying humidity (relative humidity 33 %, 65 % and 87 %), and measured changes in dimensions and mass. The bending strength and hardness of the printed parts were measured after conditioning. We found that the mass/moisture content of specimens increased during conditioning in a humid climate, which means that the content of wood in the filament affects the properties of the printed product. By testing, we found that the bending strength and hardness of printed parts are decreasing with the proportion of wood dust in the filament. There are several reasons for this: small wood particles act primarily as a filler, during printing several empty spaces and poor adhesion between layers occurs due to irregular diameter of manufactured filaments with wood particles, which causes uneven extrusion of the material through the print nozzle and with higher content of wood dust we get more nozzle clogging.