The dilatometer test is a loading test run inside a borehole with a radially expandable cylindrical probe. It is used to determine the deformability of rock mass in-situ, and the creep properties of very soft rock. The PROBEXe determines the deformations by measuring the total volume change of the probe. This method is the same well-established method used with the pressuremeter. It provides a mean modulus value of a large volume of rock, contrary to the use of callipered probes which can be affected by local heterogeneities. The volume changes of the probe are measured by monitoring the displacement of a piston. This configuration eliminates the parasitic expansion of the tubing and pumping system. The PROBEXe is a versatile piece of equipment that possesses characteristics of both a rock pressuremeter and a flexible dilatometer.