Traditionally pressuremeter tests results are interpreted using only the loading pressure–expansion data. An interpretation method has been developed that makes use of both the loading and unloading portions of a pressuremeter test and incorporates nonlinear, undrained soil behaviour. This method has been modified to handle large trains. The proposed interpretation accepts that some level of soil disturbance exists during the early stages of a pressuremeter test, and hence more emphasis is placed on the unloading portion of the test. A methodology is described to allow this interpretation procedure to be applied to self-bored, prebored, and full-displacement undrained pressuremeter tests. The proposed method is evaluated using self-boring and full-displacement pressuremeter test results from various published field projects. The interpretation is accomplished using commercially available microcomputer software that can perform the curve-matching process for both loading and unloading portions of the test. Key words : pressuremeter, loading data, unloading data.