Degradation of polymers can be thermal, photochemical, oxidative, photooxidative, ionization, mechanical and chemical. The effects of UV radiation on polymer materials are material colour change, microstructure formation on the surface and weakening of mechanical and electrical properties. Polystyrene (PS) is a thermoplastic homopolymer which, due to its good properties and low price is produced in large quantities. Polycaprolactone (PCL) is a biodegradable polymer that has prompted its extensive research for potential applications in biomedicine. The aim of this paper was to give an overview of the previous investigations regarding UV degradation of polymers and to investigate the properties of polystyrene (PS) and polycaprolactone (PCL) before and after 96, 168, 336 and 504 hours of exposure to radiation in UV chamber. Structural and surface changes caused by UV degradation of PS and PCL were investigated using FTIR-ATR spectroscopy and the contact angle measurement. Furthermore, thermal properties were investigated using differential scanning calorimetry (DSC) and mechanical properties with tensile test on mechanical testing machine. The obtained results showed that UV irradiation, for both polymers, have influence on mechanical and thermal properties, but smaller changes in structure and surface are noticed.