Problems have occurred with dykes constructed on the Lisan Marl to retain brine pumped from the Dead Sea, which is chemically processed to produce potash. In this study the engineering behavior, collapse potential and compressibility of the Lisan Marl were assessed by undertaking laboratory tests with both natural, distilled water and brine as the media. The results showed that the liquid limit and fine particles increased when the soil was mixed with fresh/distilled water compared with brine water. The soil can be classified as highly compressible with a low undrained shear strength. In terms of collapsibility, the soil could be classified as slightly collapsible upon inundation with distilled water and moderately collapsible when soaked in Dead Sea brine. The results are important when determining the height and nature of the dykes.