1. From the same organism or deriving from the same individual: "Autologous donors involve situations in which the donor and the recipient of blood, bone, skin, etc. are the same person."
2. Obtained from the same individual as the one who is providing the other constituents of an experiment or study: "A reference to autologous serums, tissues, cells, etc., that are under immunologic study."

A procedure for collecting and storing a patient's own blood several weeks before its expected need by the patient: This method of providing blood, or autologous transfusion, for an individual is done in order to prevent the transmission of diseases which can take place with the use of donor blood.

Blood that is lost during a surgical procedure can be recovered from the operation site and processed for the circulatory system when a patient's autologous transfusion is available.