This paper presents the shear strength study of a saturated and unsaturated lateritic tropical soil, via triaxial compression tests on undisturbed (loose) and compacted soil samples. The shear strength of the soil increases hyperbolically with increasing suction for both undisturbed and compacted soils. The variation of shear strength with increasing suction for the compacted soil is much greater than the variation for the undisturbed soil. It indicates that the benefits of compaction, as a soil-improving practice, can be more advantageous for unsaturated soils.