Procedure for determining the mass flow ratio (x) of a medium which is at least temporarily two-phase or multi-phase and flows through a measuring tube, with a gaseous first phase which flows at a first mass flow rate m G and with a liquid second phase which flows at a second mass flow rate m L, using a vortex flowmeter, which has a bluff body projecting into the flowing medium and a vortex sensor, particularly located downstream or inside the bluff body, wherein the gaseous phase has a first density (ρ G), which is different from a second density (ρ L) of the liquid phase, comprising: Generation de Karman vortices in the flowing medium, at least in the area of the vortex sensor, using the bluff body, wherein the vortices are shed by the bluff body at a vortex shedding frequency (f v) that depends on a current flow velocity of the flowing medium; Recording of period pressure fluctuations, caused by the Karman vortices in the flowing medium, using the vortex sensor with a view to generating a sensor signal corresponding to the pressure fluctuations; Selection of a useful signal component from the sensor signal S, said component having a frequency band, particularly a narrow band, containing the vortex shedding frequency, particularly with a relative bandwidth less than 50 % of the current vortex shedding frequency; Determination of a Froude number (Fr, Fr'), particularly densiometric, wherein the Froude number (Fr) is a characteristic variable of the two-phase or multi-phase medium flowing through the measuring tube which depends on a diameter of the measuring tube, an empty pipe velocity (u GS) of the first gaseous phase and a gravitational velocity (g), particularly according to the calculation rule: Fr = u GS D ⋅ g Use of the useful signal component and the Froude number (Fr, Fr') to determine a mass flow ratio (x) of the flowing medium, wherein the mass flow ratio (x) is defined as a ratio of the first mass flow rate m G to the total mass flow rate at which the medium flows, particularly according to the calculation rule: x = m ̇ G m ̇ L + m ̇ G. Generation de Karman vortices in the flowing medium, at least in the area of the vortex sensor, using the bluff body, wherein the vortices are shed by the bluff body at a vortex shedding frequency (f v) that depends on a current flow velocity of the flowing medium; Recording of period pressure fluctuations, caused by the Karman vortices in the flowing medium, using the vortex sensor with a view to generating a sensor signal corresponding to the pressure fluctuations; Selection of a useful signal component from the sensor signal S, said component having a frequency band, particularly a narrow band, containing the vortex shedding frequency, particularly with a relative bandwidth less than 50 % of the current vortex shedding frequency; Determination of a Froude number (Fr, Fr'), particularly densiometric, wherein the Froude number (Fr) is a characteristic variable of the two-phase or multi-phase medium flowing through the measuring tube which depends on a diameter of the measuring tube, an empty pipe velocity (u GS) of the first gaseous phase and a gravitational velocity (g), particularly according to the calculation rule: Fr = u GS D ⋅ g Use of the useful signal component and the Froude number (Fr, Fr') to determine a mass flow ratio (x) of the flowing medium, wherein the mass flow ratio (x) is defined as a ratio of the first mass flow rate m G to the total mass flow rate at which the medium flows, particularly according to the calculation rule: x = m ̇ G m ̇ L + m ̇ G.