To measure characteristics of a non-Newtonian fluid, preferably blood, a non-magnetic container is provided for receiving the fluid. A magnetic body is contained in the container, and a winding is provided around the container. An AC current supplying device is connected to the winding for supplying input AC current of different amplitudes thereto to generate magnetic fields of different strengths in the container to cause the magnetic body to oscillate at different shear rates in the fluid. A measuring device is provided for measuring amplitude and/or phase of the oscillations of the magnetic body and a shear rate determining device is provided for determining the shear rates by measuring differences between the amplitude and/or phase of the oscillations of the magnetic body and the amplitude and phase of the input AC currents. The amplitude difference at a specific shear rate is proportional to the viscosity of the fluid, and the phase difference at a specific shear rate is proportional to the viscoelasticity of the fluid.
