To fulfil its numerous science objectives, the Gaia mission needs to account for theimpact of the radiations at CCD level. Through the defects generated in the silicon, theradiations will not only degrade the overall signal-to-noise ratio of the measurements,but also corrupt them with a bias to be corrected on ground. In order to characterize thiseffect, and help deriving a proper calibration strategy, an extensive radiation testcampaign has been carried out in EADS Astrium since 2006, covering the differentinstruments and CCD variants. We present an overview of this radiation test bench, and thedifferent investigations performed so far and associated findings.