This paper deals with the failure mechanism of sedimentary rocks in terms of underground stability. The engineering behaviour of anisotropic rocks and anisotropic influence needs further investigation with regard to stability analysis due to the different failure mechanisms. In order to understand the effects of anisotropy, laminated rocks were investigated. Laboratory test results for the anisotropic strength characteristics of sedimentary rocks in different directions were determined. The material selected for the tests was sandstone and siltstone from the Upper Miocene-Pliocene Handere Formation (Th) in northern Adana (turkey). Samples were then prepared as test samples to ISRM standards with the samples orientated at 10 degrees increments to the lamination plane for the application of failure theories. The deformation characteristics of these anisotropic rocks in the application of the failure theories were determined by the lamination plane angle to the loading direction when applying the stress state. Various failure theories were applied to determine the anisotropic strength and deformation properties of these rocks. It is commonly assumed that bedding planes of sedimentary rocks exhibit homogeneous properties and it was found to be a transversely isotropic rock material.