The removal of a sample of bone marrow and a small amount of bone (usually from the hip) through a large needle. At least two samples are taken. The first is by aspiration (suction with a syringe). The second sample is a core biopsy to obtain bone marrow together with bone fibers. After the needle is removed, this solid sample is pushed out of the needle with a wire. Both samples are examined under a microscope to look for diseases, abnormalities, and a blood cell count.