Method of preparing containers for blood-derived products which comprises at least a filling phase of the blood-derived product containers with the blood-derived product; a viral inactivation phase of the blood-derived product containers; and a quality control phase for detecting possible defects in the blood-derived product containers; characterised in that the viral inactivation phase is carried out by placing the blood-derived product containers in contact with steam at sub-atmospheric pressure in a chamber adapted for that purpose.PROCEDIMIENTO DE PREPARACIÓN DE CONTENEDORES DE PRODUCTOS HEMODERIVADOS