Abstract The matrix of four slopes of Pinousuk Gravel from Mesilou, Kundasang, Sabah namely S1, S2, S3 and S4 were collected for physical and engineering analysis. The slope stability analysis is conducted by using Fellenius slicing method. Pinousuk gravels which originated from the glacial deposits of Mount Kinabalu during Pleistocene age consist of mixture of various sizes and types of rocks such as ultrabasic rocks and granodiorite. Engineering properties of slope’s matrixes show high to very high plasticity with the appearance of smectite and illite as clay minerals. Based on direct shear test, value of cohesion (c), friction angles (°) and shear strength (τ) of the slopes can be obtained. The results show the value of shear strength range from 7.5 kPa (S3) to 13 kPa (S2), while friction angles range from 11° (S3) to 22° (S2) and the cohesion values range from 2.1 kN (S2) to 3.1 kN (S1). Slope is considered stable if the value of factor of safety (FoS) is ≥ 1 and indicates unstable if it is less. Slope S1, S2 and S4 are considered as stable slopes with FoS value ranges from 1.09 to 1.45. S2 is the most stable slope due to its highest friction angle and shear strength of the matrixes among bigger size of ultrabasic fragments which increase the interlocking between particles. While S3 which is dominated by smaller ultrabasic fragments is considered as unstable with FoS value of 0.97 due to the lowest shear strength and friction angle which encourage the collision between particles for slope failure to occur.