The results obtained from six different types of triaxial tests on five undisturbed clays are presented and discussed. It is shown that the shearing resistance with respect to effective stress is, for all practical purposes, independent of the stress path followed to failure, provided that the failure criterion of maximum principal effective stress ratio is considered. If the failure criterion of maximum principal stress difference is adopted, then the shearing resistance obtained from undrained tests is generally about 8 per cent less than that obtained from drained tests. The importance of the influence of the rate of strain for both drained and undrained tests is emphasized.