The invention relates to an irradiation apparatus for inactivating pathogens and/or leukocytes in a biological fluid such as a platelet suspension and/or plasma comprising : a casing 2, a support member 3 for carrying at least one irradiation bag containing the biological fluid, a light source 4 comprising two banks of light 5,6 disposed above and below the support member 3, and an agitating system 25 for moving the support member 3, the light source generating UVC light of suitable intensity to inactivate pathogens and/or leukocytes and the agitation system moving the support member in an orbital path with predetermined with predetermined amplitude and rotational frequency suitable to expose the whole biological fluid to UVC.
