The aim of this paper is to study the influence of total suction on some physical/mechanical properties related to argillaceous rocks from the Colombian Andes. A wetting path was applied to the rocks using the vapor transfer technique with continuous recording of mass and deformations. Uniaxial compression tests were conducted on specimens at different levels of suction. In addition, microstructural observations are carried out using a Mercury Intrusion Porosimeter Apparatus. Results from the laboratory tests indicate that anisotropic deformations took place during the wetting path. Also, total suction contributed to a considerable and non-linear reduction in the compressional wave velocity, peak compressive stress, and elastic modulus of the tested samples. Microstructural analysis indicated the influence of the size and number of the pores in the samples on their high levels of suction.