Abstract: In the method for mass flow measurement by the Coriolis principle a fluid-traversed elastically deformable measuring tube is periodically deflected. As a measure of the mass flow phase displacements are measured between deflections of portions of the measuring tube wall which are arranged differently in the flow direction. For this purpose a periodic deformation of the cross-section of the measuring tube is effected in such a manner that portions of the measuring tube wall lying diametrically opposite each other are deflected in each case through about the same distance in opposite or the same direction transversely of the flow direction of the fluid. This method can be carried out with a simply constructed mass flow meter in the operation of which a wandering of the center of gravity of the meter is substantially avoided and which is also suitable for large nominal widths.