The HERA-B Vertex Detector System (VDS) is a Roman Pot system integrated into the proton ring of the HERA accelerator at DESY and serves as an independent part of the tracking system of the HERA-B forward spectrometer. The performance of the VDS meets the design specification. It is based on double-sided silicon micro-strip detectors which are operated as close as 1 cm to the beam and are thus exposed to extremely high and inhomogeneous radiation levels. At the design luminosity the peak irradiation is around 3×10 14 minimum ionizing particles per cm 2 per year. Test measurements have shown adequate radiation tolerance on the required time scale of 1 year. New long-term studies presented here indicate that on periods longer than 1 year charge collection efficiencies might drop.