Concrete is an important material used in all kind of building construction and ordinary Portland cement (OPC) is one of an important element in the production of concrete. However, the production of cement causes a problem because of high CO 2 emission to atmosphere. The manufacture of 1 tonnes of cement would produce approximately released 1 tonnes of CO 2. So, the need to search another material that can replace a cement with same properties and environmental friendly are crucial. The suitable material to replace cement has to be a pozzolanic materials. This is because pozzolanic materials has cementitious properties and high silica content. Palm oil fuel ash (POFA) and sugarcane bagasse ash (SCBA) are the material that suitable to replace cement because of high silica content. The use of POFA and SCBA in concrete has been studied by many researcher and it has been proved to improve the mechanical strength of the concrete either in normal concrete, high strength concrete or lightweight concrete. This paper would discuss the overview of the previous study on the cement replacement by POFA and SCBA and the potential of the both materials to be mix together to improve its properties. The chemical element which will be the focus point is SiO 4 , MgO, CaO and SO 3 , while the physical and mechanical properties such as workability, specific gravity, compressive strength and tensile strength will also be reviewed.