Bone marrow was removed from long bones of living rabbit by drilling openings at both ends of the bone and expressing the complete marrow with mineral oil or saline, using a silver cannula and the syringe. A single opening is drilled at one end and 4 openings at the opposite end, which is then enlarged by the removal of the spicule of bone. The Ag cannula is inserted into the single opening. This method allows a study of marrow regeneration and may serve as a test procedure.