One of the most important characteristics of argillaceous rocks is their swelling potential. This can be determined either by direct or indirect methods. Conventional tests are performed in which one of the properties/indices of rock is associated with the swelling potential. Since the direct tests are usually costly and time consuming, this article is focused on introducing a new method for evaluation of the swelling potential of argillaceous rocks. This is a quicker and less expensive test. The present study shows that there is a good correlation between “Contact Angle” of a drop of water on a flat rock surface with its swelling potential. Since the swelling potential is associated with molecular structure and surface tension of molecules, it is expected that contact angle (which is also influenced by this surface tension) be correlated with swelling potential. In the present study, free swelling, contact angle, plastic and liquid limit tests are conducted on rock samples and their correlations are determined. The results showed that although there is an exponential relationship between plasticity index and swelling strain, using this parameter as an indirect method for swelling evaluation, has some limitations. On the other hand, due to the ability of contact angle to distinguish rocks with different swelling potentials, using this parameter has been proven to be an appropriate criterion for assessment of swelling potential.