As part of the AACR Annual Meeting Methods Workshop ''Sample Collection, Processing, and Storage for Large-Scale Studies: Biorepositories to Support Cancer Research,'' blood specimen collection, processing, storage, and dissemination issues were discussed. Whole blood and blood fractions comprise a major portion of biospecimen collections for population-based studies. Although procedures for collecting, processing, storing, and shipping blood components are generally standardized and well documented, several important factors need to be considered before a new study involving blood collection is initiated. Blood is collected from study participants for a variety of purposes, including as a source of DNA, and for a variety of laboratory analyses that may be done on whole blood or blood fractions, including serum, plasma, and lymphocytes. Blood or blood fractions may be shipped to laboratories and biorepositories either at ambient temperature, cooled or frozen, depending on the intended analyses. Blood processing may include fractionation, cryopreservation to preserve the viability of lymphocytes, or purification of nucleic acids. The proper storage conditions depend on a variety of factors, including the intended analyses and whether the specimens will be used within a short period or need to be stored for longer periods. As for all laboratory and biorepository procedures, blood collection, shipment, processing, and storage should be conducted under a strict quality assurance program, including standard operating procedures and regular quality control reviews.