Abstract: The invention relates to a metering pump for liquid and gaseous media, which is provided with a deformable tube for the medium to be conveyed. The pump casing accommodates a rotating member which squeezes the tube against an inside surface in the pump casing. The tube is guided around the rotating member constituting a main eccentric, through a looping angle of 360.degree.. A secondary eccentric, the diameter of which is smaller than the diameter of the main eccentric, is mounted on the shaft of the main eccentric. The main eccentric is a ball bearing, the outer race of which clings to the tube by surface adhesion during rotation of the shaft. The ball bearing is rotated with the rotating shaft, while the outer race performs a radial reciprocating motion, thus avoiding any flexing of the tube, which is merely cyclically compressed and released again.