Method of preparing containers for blood-derived products which comprises atleast a filling phase of theblood-derived product containers with the blood-derived product; a viralinactivation phase of theblood-derived product containers; and a quality control phase for detectingpossible defects in theblood-derived product containers; characterised in that the viral inactivationphase is carried out byplacing the blood-derived product containers in contact with steam at sub-atmospheric pressure in achamber adapted for that purpose.