Abstract: A core-severing cannula for use with tissue biopsy devices, comprising a plurality of flexible fingers for severing a tissue core. The core-severing cannula is positioned coaxially outside of a core-cutting cannula, and is slidable relative to the core-cutting cannula. As the device is activated, the core cutting cannula and core-severing cannula advance together to cut a core of tissue. Subsequently, the core-severing cannula is advanced relative to the core cutting cannula, and the fingers of the core-severing cannula assume a closed position to sever the core from the target site.