In our previous works (Baykin and Golovin 2016, 2017) it is shown that inhomogeneity of the permeability of a reservoir might play a significant role in the choice of the direction of the hydraulic fracture propagation. This effect was demonstrated using the fully coupled model of the hydraulic fracture in the poroelastic medium under the restriction on the geometry of the fracture similar to the one used in the Khristianovich–Geertsma–de Klerk model. In present paper, we extend our observations to a model of the planar 3D hydraulic fracture in the inhomogeneous poroelastic medium. In a series of numerical experiments we demonstrate that, depending on the permeability contrast of different parts of a layered reservoir, the hydraulic fracture propagates either within the low-permeable or the high-permeable zones of the reservoir. This behaviour is explained by the non-uniform action of the backstress that is formed on the fracture walls due to the pressure of the pore fluid.