Foaming processes for polymeric materials are usually carried out using extrusion and injection methods. This applies primarily to products whose wall thickness is at least 4 mm. The main advantage of using this type of modification is the continuity of the film, without holes and depressions on the surface and a reduction in the density of the product. Foaming of plastics using the blown extrusion process, where we obtain thin-walled products in the form of film, involves the risk of loss of it continuity. Additionally, as a result of modification with blowing agents, the obtained film is porous throughout its cross-section, which causes surface irregularities that affect its tribological properties. The article presents the results of research on selected mechanical and tribological properties and structure of microporous films obtained in the blown extrusion process. The tests showed the influence of the blowing agent used on the tested properties and structure of the film.