Bovine leukemia virus (BLV) is the etiologic agent responsible for enzootic bovine leukosis. Detection of cattle seropositive for BLV and laboratory studies of BLV require the preparation of large quantities of BLV antigen. A convenient and economical method for concentrating virus from large volumes of cell culture medium involves the precipitation of the virus in the cold by polyethylene glycol (PEG). The present work demonstrates the feasibility of rapidly precipitating BLV with 10% PEG and subsequently separating the resuspended virus from the residual PEG on a disposable desalting column.