Abstract: The magnetic anisotropy field in a layer of magnetic material on a substrate is determined by a method involving the application of a magnetic field upon whose release a so-called "sea of bubbles" is observed. The direction of this field typically is at a nonzero angle of elevation relative to the layer.In accordance with the invention, a preferred angle of elevation is determined upon inspection of a functional relationship between angle of elevation and magnetic field strength associated with the observation of a sea of bubbles. Results obtained by the method compared favorably with results obtained based on magnetic resonance techniques and, since the method is also relatively simple, it is particularly suitable for quality control in the manufacture of magnetic bubble devices.