The main aim of this paper is to present the research findings regarding the recovery possibilities of plastic and wood raw wastes. One of the recovery possibilities for mentioned raw materials is production of waste raw materials based wood-plastic composites (WPC). Lonely production process is influenced by technological and raw material parameters (type of raw material and particle size) and thus the final quality and mechanical properties of WPCs have to be determine. This paper also presents the results of realized experimental research which dealt with the determination of relationship between material parameters and mechanical properties during production of WPCs. The main goal of presented paper is to determine the mutual interaction between mechanical properties, type of the plastic matrix used in WPC, wood/plastic concentration ratio and particle size of wood sawdust used in WPC. In this paper the authors also comparing mechanical properties of WPCs based on recycled and original plastics. As a plastic matrix 100 % original HDPE and recycled HDPE originating from lids of PET bottles was used. Obtained research findings can be very helpful at WPCs production and shown the possibility of using also waste raw materials for WPC products, and thus increase the environmental responsibility with the environment protection.