The purpose of this International Standard is to give an overview of the minimum requirements of process and quality-control components of the cytogenetic response for triage of mass casualties. Cytogenetic triage is the use of chromosome damage to evaluate approximately and rapidly radiation doses received by individuals in order to supplement the early clinical categorization of casualties. This International Standard concentrates on organizational aspects of applying the dicentric assay for operation in a triage mode. The technical aspects of the dicentric assay can be found in ISO 19238. This International Standard is applicable either to an experienced biological dosimetry laboratory working alone or to a network of collaborating laboratories (as defined in Clause 9).