One parameter needed for the stability analysis of seafloor mud‐covered slopes is the undrained shear strength, cu, of the mud. A literature review dealing with mudslides shows that six methods exist to measure the cuof muds either in the laboratory or in the field. These methods are: 1) the vane shear test, 2) the cylinder‐strength meter test, 3) the sphere‐strength meter test, 4) the cone penetrometer test, 5) the pullout test using a cylinder, and 6) the use of the vertical profile of a mudslide in the direction of movement. The present study reports a laboratory investigation of the undrained shear strength of artificially prepared muds using the six methods in order to evaluate their accuracy.