Presents the results of investigations performed at the Swedish Geotechnical Institute (SGI) regarding different systems used for measuring pore pressure. The purposes of the investigation were: (a) to study the behaviour of different systems when measuring natural variations in the groundwater conditions ; (b) to study the influence of changes in atmospheric pressure on the measurements; (c) to determine the essential characteristics of a measuring system (piezometer and recording instrument) required for reliable long-term measurement of pore pressure.