An improved biopsy needle assembly for efficient removal of multiple biopsy cores from a single needle penetration. The needle apparatus comprises an elongate assembly of paired sleeves with an open notch in the wall of the outer sleeve for engaging a tissue volume in the bore of that sleeve. An inner sleeve or blade member with a sharp blade edge is moveable from a retracted position to an extended position to both (i) excise the tissue volume, and (ii) function as valve means to alter the open notch between an open position and a closed position. The invention provides a looped inflow-outflow passageway system for using high-pressure fluid flows to push or expel the excised tissue from the bore in working end where the excised tissue is captured. The looped passageway system is coupled to a remote pressurization source.