Blood was drawn from ten healthy volunteer donors into citrate-phosphate-dextrose (CPD) anticoagulant and placed on the quarantine shelf of the blood bank refrigerator. Plasma dextrose, sodium, potassium, chloride, bicarbonate, GOT, LDH, and hemoglobin as well as WBC, hematocrit, MCV, MCHC, whole blood pH, and ammonia were measured on all samples initially and at one, two, seven, 14, 21, and 28 days of storage at 4 C. Whole blood lactate also was analyzed serially on five of the units. An additional 27 units of CPD bank blood (two to 21 days of age), routinely processed, handled, and stored by the blood bank, were submitted to the same analyses on the day of administration to the patient. Five of these processed units, 21 days old, were resampled at 28 days. Results of the analyses are presented and discussed. The most pronounced changes were seen for dextrose, potassium, bicarbonate, lactate, LDH, ammonia, and hemoglobin. Plasma dextrose and bicarbonate declined in concentration while potassium, lactate, LDH, ammonia, and hemoglobin rose with storage. In general, changes in the regularly processed, singly sampled bank units were greater than those observed in the specially processed, quarantined units sampled serially. This study indicates that routine transportation, processing, and handling of bank blood may lead to increased biochemical alteration.