A tissue-removing catheter (10, 10', 10") for removing tissue from a body lumen, the catheter comprising: an elongate body having proximal and distal ends; a tissue-removing element adjacent the distal end of the elongate body, the tissue-removing element configured to engage and remove tissue from the body lumen; a tissue-containment chamber (17, 17', 17") adjacent the distal end of the elongate body and defining a window through which the tissue-removing element is partially extendable, the tissue-containment chamber (17, 17', 17") configured to receive tissue removed by the tissue-removing element when the tissue-removing element partially extends through the window, the tissue-containment chamber (17, 17', 17") further defining a chamber lumen and having a proximal end connected to the distal end portion of the elongate body, a distal end opposite the proximal end, a longitudinal axis extending between the proximal and distal ends, and a tissue-removing opening (52, 52') adjacent to and spaced apart from the distal end thereof; and a closure component (54, 54', 54") in the chamber lumen of the tissue-containment chamber (17, 17', 17"), the tissue-removing catheter (10, 10', 10") characterised in that the closure component (54, 54', 54") is slidable longitudinally within the chamber lumen between a closed position, in which the closure component (54, 54', 54") inhibits removed tissue in the tissue-containment chamber (17, 17', 17") from exiting through the tissue-removing opening (52, 52'), and an open position, in which the closure component (54, 54', 54") allows removed tissue in the tissue-containment chamber (17, 17', 17") from exiting through the tissue-removing opening (52, 52'). an elongate body having proximal and distal ends; a tissue-removing element adjacent the distal end of the elongate body, the tissue-removing element configured to engage and remove tissue from the body lumen; a tissue-containment chamber (17, 17', 17") adjacent the distal end of the elongate body and defining a window through which the tissue-removing element is partially extendable, the tissue-containment chamber (17, 17', 17") configured to receive tissue removed by the tissue-removing element when the tissue-removing element partially extends through the window, the tissue-containment chamber (17, 17', 17") further defining a chamber lumen and having a proximal end connected to the distal end portion of the elongate body, a distal end opposite the proximal end, a longitudinal axis extending between the proximal and distal ends, and a tissue-removing opening (52, 52') adjacent to and spaced apart from the distal end thereof; and a closure component (54, 54', 54") in the chamber lumen of the tissue-containment chamber (17, 17', 17"), the tissue-removing catheter (10, 10', 10") characterised in that the closure component (54, 54', 54") is slidable longitudinally within the chamber lumen between a closed position, in which the closure component (54, 54', 54") inhibits removed tissue in the tissue-containment chamber (17, 17', 17") from exiting through the tissue-removing opening (52, 52'), and an open position, in which the closure component (54, 54', 54") allows removed tissue in the tissue-containment chamber (17, 17', 17") from exiting through the tissue-removing opening (52, 52').