Nowadays DC operation of cable systems is increasingly preferred to AC operation at MV level due to low power losses and an increasing number of decentralised producers and consumers. That is why already laid, ACstressed XLPE cables are to be operated at MVDC to increase the transmission power. Therefore, an XLPE specimen with an inserted needle is utilised to investigate the PD behaviour under successive MVAC and MVDC stress. The measurements show a significant decrease of the inception voltage at AC operation for DC pre-stressed specimens. One possible reason is the accumulation of space charges in the insulating material.