Abstract: The sisal fibre is randomly included into the soil at three different percentages of fibre content, i.e. 0.2%, 0.4% and 0.6% by weight of cohesive soil. Three different lengths of fibre, i.e. 0.5, 1.0 and 1.5 cm are also considered as one of the parameters in this study. Unconfined compression strength and shear strength of sisal fibrereinforced soil has been undertaken to compare with the soil sample without sisal fibre. The test results show that unconfined compression strength and shear strength of cohesive soil are significantly improved. With the increasing percentages of fibre content and lengths of fibre, the unconfined compression strength and shear strength increase gradually. When the percentages and length reach certain values, the unconfined compression strength and shear strength still increase, but the growth slow sharply.