It IS important to estimate the magnitude of settlement and the time of primary consolidation in geotechnical engineering projects. For these purposes, site explorations and laboratory tests are usually performed. However, the mechanical properties determined from laboratory tests on the samples obtained by different sampling techniques show different trends. In this study, three types of consolidation test were carried out on the soil samples obtained by three different sampling techniques (76mm tube, 76mm piston, and block samples), to verify the effect of sample disturbance on consolidation properties. It was found that sampling methods have influence on the c - log a ` v relationship. While insignificant difference of compression indices from the samples obtained by different sampling techniques was observed in compression region, these values showed a different trend in recompression region. The values of cv and k of block samples had a tendency to be larger than those of piston and tube samples. At consolidation pressure larger than ap` , however, these properties became similar regardless of sampling methods. The block and piston samples gave slightly higher values of Ca/ce than tube samples. In the results of ILEoP and CRS test, it was observed that the values of a`p measured / a`p best estimated of Yang-San clay decreases when strain becomes larger than 1.0% and that recompression strain of block samples is in the range of 1.5-2.0% while those of piston and tube samples are 1.75-3.75%. It was also shown that the values of ap` of block samples exceed those of piston and tube samples by about 6-10%.