The effect of saw dust ash on index and engineering properties of a weak lateritic soil was carried out in this study. Specimens prepared from lateritic samples were tested for its gradation (sieve analysis), unconfined compressive strength (UCS) and compaction parameters (MDD and OMC) at energy level of British Standard Light (BSL). The samples were admixed with varying percentages of saw dust ash (SDA) and the tests were repeated on the admixed samples. The general trend of the results shows that the gradation of the soil improved from A-7-5 to A-5 at 4% SDA content by American Association of State Highway and Transportation Officials (AASHTO) soil classification system, UCS values also peaked to 237.12 kN/m2 at 4% SDA content while the compaction parameters were still best at the natural stage at BSL energy level. The peak UCS value, though, shows an improvement of 26.9% when compared to that of natural soil, it still falls below the minimum specified value for base material stabilization using OPC (1710 kN/m2) as well as that for sub-base material (687-1373 kN/m2). From the work, 4% stabilization of weak lateritic soil with SDA can improve some index and engineering properties of a weak lateritic soil. It is also evident that the resulting stabilized soil should not be used for pavement construction. Nevertheless, addition of 4% SDA to weak lateritic soil should be encouraged when slight gradation improvement is the only target. Keywords: index properties; engineering properties; lateritic soil; saw dust ash; stabilization.