This work was carried out to assess the spatial distribution of Magnesium, Potassium and Sodium in sediments from Sadong River in Malaysia. These elements are fractionated by grain size due to suspended particulate matter and river bank deposits. The aim of the study includes the determination of the concentration of Mg, Na and K in sediments from Sadong River, investigation of the effects of grain size on the elements and elucidate the origin of these elements. Bedrock lithology had a major influence on the geochemistry of the river sediments. The levels of Mg, K and Na in Sadong River was influenced by natural factors and minimal impact of anthropogenic activities.