Pre-consolidation pressure is a very important parameter, which describes the stress history and affects the behavior of cohesive soils in geotechnical engineering. The pre-consolidation pressure of a soil sample is generally determined by using a graphical procedure apllied on experimental results. This study is concerned with the improvement of this experimental approach. Clay samples were preloaded in slurry consolidoemeter and Rowe cell, and remolded samples were prepared in the laboratory under controlled conditions. Some Rowe cell samples and remolded samples were prepared under various isotropic and anisotropic stress conditions in triaxial test cells. After preparation of samples, oedometer tests were conducted on all samples. The pre-consolidation pressure values were then determined by implementing various methods published in geotechnical literature. These include Casagrande, Schmertmann, Janbu, Butterfield, Tavenas, Burmister, Old and Van Zelst methods. These methods were evaluated by regression analyses and the known pre-consolidation pressure values. A new pre-consolidation pressure determination method, generally based on the Tavenas method, is suggested based on comparisons with all existing methods.