This paper analyses the results of undrained cyclic torsional shear and compression loading triaxial tests run on undisturbed Noto soil. The cyclic torsional shear test was performed under stress control while the compression loading triaxial test was performed under strain control. The possibility of modelling the degradation behaviour of clays with a simple law is examined. In particular, the case of one-dimensional loading is considered. On the other hand the degradation parameter (t) proposed by Idriss et al.(1978) for cyclic tests under controlled-strain loading conditions was also computed according to the procedure suggested by Lin and Chen (1991) for stress-controlled tests.