The important requirements for civil engineer are economic and technical in the field and this appears in fill work. The civil engineer needs a suitable soil for fill works, so the expansive soil is studied as one of the possible solution. For this research the physical, mechanical and field tests are performed. The purpose of the present paper is examining the distribution of lateral swelling pressure developed in clay soils on retaining walls after adding water and to predict the values and shape of pressures distribution for design purposes. So, five cells of strain gauges were prepared, the distance between them equals 50cm. and they were fixed at wooden sheet on bedroom's wall in one of Assiut el gadida city projects. Prediction of lateral earth pressures has been a problem to civil engineers for a long time. The first rational approach by which lateral earth pressures could be estimated was simple and practical, and they have come to be known as the classical methods of prediction of lateral earth pressure. The behaviour of soil is swelling after adding water then affects on retaining structures. The effect of soil is depending on many factors like water content, depth, the type and quantity of mineral in soil composition, the time, … etc. The results of this research give a good knowledge about the value and the distribution of lateral swelling pressure, and the results showed that the swelling pressure on retaining structure increases by increasing the water content and montmorillonite minerals content in soil. Then, the results enable the civil engineers to attain safe and suitable design for retaining structure without engineering problems...