In order to delineate effects of surface roughness on the unit shaft resistance, a research program comprising 25 loading tests was carried out on 44 mm diameter model piles, with different surface roughness, embedded in dry natural fine sand mass. In all tests the loading level was increased until the soil failed. The results obtained from this study indicate that pile surface roughness enhances the tendency of the sand to dilate during loading, which in turn increases the magnitude of the radial effective stress against the pile surface. Also, the results indicate that the pile shaft resistance increases due partially to the fact that the sand mass-sand paper interface friction angle increases as the sand paper roughness increases. However, it also depends on the rise of radial effective stress due to dilation of sand during loading.