The article contains the results of the shear strength tests of cohesive soil taken from the landslide in Targanice near Andrychów. In order to determine the impact of moisture content (Sr = 0.42 and 1.00), degree of compaction (IS = 0.78, 0.93 and 1.00) and a shear velocity (vs = 0.1, 1.0 and 10.0 min · mm–1) on the values of parameters characterizing the shear strength, that is the angle of internal friction and cohesion, two of the above mentioned factors were assumed as constant and the influence of the third was tested. The tests were carried out in a direct shear apparatus, in a box with a cross section 12 × 12 cm, with intermediate frames forming a shear zone of a thickness of 1.0 cm. It was pointed out that the test procedure significantly influences the obtained results, so it is important its correct choice depending on the purpose for which shear strength parameters of the soil are determined. This is essential in the designing and construction of all types of engineering structures in the field of foundation and earth structures.