Abstract: The invention relates to a high-vacuum molecular pump of the kind comprising at least two coaxial elements (1 and 2) mounted rotatably with respect to each other and at a small distance from each other, wherein a side of one of the elements (1) positioned opposite a side of another element (2) is provided with at least one helical groove (5), and wherein a pump space (6) is present between these two sides of the elements, which pump space (6) is in communication with a gas supply (7) and a gas discharge (10, 8). Between the gas supply (7) and the pump space (6) a substantially annular gas supply chamber (9) is present, which is bounded by the elements (1 and 2) and which is relatively wide near the gas supply (7) but narrows downstream towards the pumpspace (6). The helical groove (5) extends into the annular gas supply chamber (9).