Abstract When pressure is applied to the saturated clay, the clay will not let the water out immediately due to low porousness. Thus the failure occurs in the so called undrained state. For measuring the undrained shear strength we use field and laboratory tests. In this graduation thesis we investigate the undrained strength of the dredged mud from the Port of Koper and bentonite by using three different methods: the vane shear probe, the cone penetrometer probe and the uniaxial compressive strength. We analyse and compare results, as well as the advantages and disadvantages of the methods used.