A number of production lots of an intravenous preparation of 4.3 g/dl of human albumin failed to EP pyrogen test when tested in three rabbits. Several lots were reprocessed and subsequently proved satisfactory but over thirty lots were placed in storage and monitored by both the EP test and by using the LAL test over a period up to 650 days. The majority of the lots showed a steady fall in the pyrogen response by both tests. These lots were removed from storage and reprocessed by sterile filtration and dispensing into new glass containers. Further examination of the product showed it to be satisfactory in all regards. The product of several lots was used in treatment episodes involving the use of cell separators and shown to be satisfactory in clinical use. The remaining lots were also issues for general clinical use without incident.