Polymeric materials are very widely used in the manufacturing of products in all industrial sectors. Their popularity is associated with a relatively low price, very good price-performance ratio and high availability, as well as significant possibilities of modification of physical and functional properties. One of the disadvantages of polymer materials is their susceptibility to changes in their properties under the influence of chemical and physical factors occurring in the conditions in which they are used. Due to the increasing application of polymer materials in various industries, there is a need to test polymer materials in terms of these complex processes. This work presents experimental studies on changes in the physical properties of poly(oxymethylene) (POM) exposed to UV-A and UV-B radiation under accelerated conditions. Additionally, the ageing process was carried out under natural weathering conditions for 3 years and thermal ageing at elevated temperatures of 90 and 130 °C. The effects of these factors were then analysed in terms of changes in tensile strength and impact strength. The research was supplemented with measurement of the weight of mouldings made of POM and aged in various conditions. The obtained results showed that ageing under accelerated conditions causes the greatest changes in the physical properties of the tested samples. Additionally, it was found that tensile strength and impact strength decreased with increasing ageing time.