A medication that is a genetically produced form of a naturally occurring hormone in the body. This drug directly stimulates the bone marrow to produce more red blood cells. Use of EPO is increasing in preoperative and postoperative settings to stimulate the patient's red cell production. It may be of benefit in acute surgical settings, and may permit more rapid recovery in the post-op period. In particular, it may be a useful adjunct following perioperative hemodilution.