Abstract: The device is comprised of a guide tube having an inner end cutting edge and during insertion, carries a stylet to prevent the collection of blood and skin tissue. Adjustable guard means are on the tube for predetermining and limiting the depth of entry. After the tube has been inserted to the proper depth, the stylet is removed and a hollow needle is inserted through the tube and the bone structure into the marrow cavity to obtain a marrow sample. There are means on the needle to provide for the predetermined and limited depth of entry of the needle and motor means are provided to rotate the needle to cut through the bone and enter the marrow cavity to obtain a marrow sample. In addition after the needle has been removed, the guide tube is adapted to penetrate the bone and be moved into the marrow cavity, at which time aspiration means are connected to the outer end of the tube to aspirate marrow into the aspiration means.