Computer simulators of hydraulic fracturing rely on known physical properties of the reservoir, in particular, the leak-off coefficient and the confining in situ stress. This information can be obtained from the solution of the inverse problem by analyzing of the pressure decline curve (PDC) in pump-in/shut-in tests. The goal of the present work is to demonstrate that poroelastic effect can have significant influence on the behavior of the PDC and, hence, to results of its analysis. For computer simulations we use the mathematical model of the hydraulic fracture in poroelastic medium developed in . We investigate the dependence of the PDC on the closure stress and of the rock permeability. It is shown that classical methods for interpretation of PDC can lead to a significant error, in particular, in estimation of the minimal in situ confining stress.