Low density polyethylene (LDPE) is a usual material used within high voltage insulation systems. Like all polymers, this material may be aged after working under high voltage for a long time. The ageing process of this ma-terial is essentially caused by external factors. The exhibition to ultraviolet (UV) radiation is one of these factors. This work investigates the effect of this constraint on the electrical and mechanical properties of LDPE after UV-ageing. This paper includes the sample preparation process, the ageing of sam-ples under identical conditions for up 380 h and finally the analysis of electrical and mechanical properties after the ageing process. The obtained results show that these properties are considerably affected by the ultraviolet radiation