Pre-consolidation pressure is an important parameter, which influences the stress history and behaviour of cohesive (clayey) soils in geotechnical engineering. Pre-consolidation pressure has so far been determined generally by graphical methods. In this study, samples were prepared, pre-loaded in he slurry consolidometer instrument, Rowe cell and by remoulding, under laboratory conditions. Some samples from the Rowe cell and remoulded ones were subjected to triaxial isotropic and anisotropic stress conditions and all samples were subjected to eudometer tests. Test results were applied to various pre-consolidation determination methods supplied in the literature (Casagrande, Schmertmann, Janbu, Butteifield, Tavenas, Burmisted, the Old Method and the Van Zelst Methods) and to be able to compare results, regression analysis was applied to the pre-consolidation pressure values that are abtoined. As a result of these a "new" method, based on the Tavenas method is proposed.