In mining design studies, the determination of the in situ strength parameters of a rock mass is difficult, expensive, and time consuming. Therefore, designers prefer an empirical approach, which has been developed based on laboratory studies. However, the scale effect on uniaxial compressive strength (UCS) is an important parameter, particularly for special materials like coal and rock salt. The accurate determination of UCS under laboratory conditions makes it possible to reliably estimate in situ strength. In this study, the change in UCS attributable to scale was determined for Nevsehir-Gülsehir rock salt, and the results are presented to emphasize the importance of the scale effect on failure phenomena in rock salt under uniaxial compression. With statistical analysis, the critical height/diameter and height/width ratios were determined to be 1.5 for core specimens and 2.0 for prismatic specimens.