The purpose of this study is to examine the design of hydrostatically balanced bearings as used in the slippers of high pressure axial piston pumps, and to outline a design procedure whereby the slipper behaviour, minimum film thickness and loss of high pressure fluid can be estimated. It is shown that for successful operation the slippers need to have small amounts of non-flatness on the running surfaces. In addition, good agreement between the measured and calculated film thickness is demonstrated.