Abstract: An entrainment pump for viscous fluids comprising a moving member which dips into the fluid and of which a flat wall cooperates, without contact but with a very small clearance, with seals provides on the sides and at the rear end of a static element consisting of a box guide elongate in the direction of movement of said moving member, in this guide there being provided successive trap chambers which with said moving flat wall form clearances progressively decreasing in the direction of said movement and of the same order of magnitude as the particular thickness of the dragged fluid. Preferred embodiments are also provided.