This International Standard recommends the handling, documentation, storage and processing of venous whole blood specimens intended for circulating cell free DNA (ccfDNA) examination during the pre-examination phase before a molecular assay is performed. This International Standard covers specimens collected in venous whole blood collection tubes. This International Standard is applicable to molecular in vitro diagnostic examinations including laboratory developed tests performed by medical laboratories. It is also intended to be used by laboratory customers, in vitro diagnostics developers and manufacturers, but also pertains institutions and commercial organizations performing biomedical research, biobanks, and regulatory authorities. CcfDNA profiles can change significantly after blood collection from the donor (e.g., release of genomic DNA from white blood cells, ccfDNA fragmentation and ccfDNA quantity change). Therefore, special measures have to be taken to secure good quality blood samples for ccfDNA examination and storage. Different dedicated measures need to be taken for preserving blood genomic DNA, which are not described in this International Standard. Blood genomic DNA is covered in ISO 20185-2, Molecular in vitro diagnostic examinations – specifications for pre-examination processes for venous whole blood – Part 2: Isolated genomic DNA. NOTE – CcfDNA obtained from blood by the procedures suggested in this document can contain DNA present in exosomes. Pathogen DNA present in blood is not covered by this International Standard. Different dedicated measures need to be taken for preserving DNA in circulating exosomes, which are not described in this International Standard. NOTE – International, national or regional regulations or requirements may also apply to specific topics covered in this International Standard.