A lot of researchers are closely connected withnatural, lignocellulose fibre containing bio-compositesproducing and studies. Various of polymer matrices,mainly polyolefins, combinations with natural fibres asa reinforcement are used. Our studies are focused onpolypropylene based bio-composites containing birch plywood production by product sanding dust (PSD) acceler-ated weathering processes. The nine groups of the samples with different composition were exposed in an ac-celerated weathering chamber for a total duration of the1032 h. The surface colour, gloss, whiteness degree, microhardness and the tensile properties of the samples duringthe weathering were tested. In addition, the weathered surfaces were characterized by scanning electron microscopy(SEM) studies and by differential scanning calorimetry(DSC) investigations. The obtained results showed the following sight: after the weathering the surface of all sam-ples is faded, also the changes of the gloss and of the white-ness degree occurs, but microhardness of the surface ofspecimens has decreased. The tensile strength of the sam-ples changes a little, in the same time the tensile modulusincreases significantly due to the decrease of the deforma-tion ability of the polypropylene matrix and recrystalliza-tion processes in PP. The SEM images taken at the 100 and500 times of the magnification revealed a lot of the differ-ent shape and sizes cracks on the surface of the weatheredsamples. DSC measurements showed the increase of thedegree of crystallinity of the polypropylene after the weath-ering due to the recrystallization process in the polypropylene matrix