Geological, petrophysical and geomechanical properties of petroleum source rocks systems vary considerably according to the depositional environment (depth, organic content, thermal maturation, and mineralogical composition, among others). Such variations result in significant property changes regarding the orientation with respect to lamination, and the scale of the analysis. Understanding of anisotropy is essential for an accurate estimation of the stress distribution and hydraulic fracture initiation and propagation; including orientation, branching, and arrest of induced fractures.This study presents a set of geomechanical tests performed on samples from the Vaca Muerta Formation in order to characterize the rock mechanical properties subjected to hydraulic fracturing. The samples come from well cores and outcrops and cover a wide variety of lithologies within the sedimentary sequence from base to top. The results show a significant variability of unconfined compressive strength, tensile strength, and fracture toughness. The most important controls are the lithology, the orientation with respect to lamination, the rock density, and the presence of natural fractures or heterogeneities. The obtained results suggest that lamination, pre-existing fractures, beef beds intercalations, volcanic ash-beds, and carbonate concretions within the Vaca Muerta Formation, can have a significant impact on hydraulic fracture propagation and geometry.