An oscillatory flow regime of the formation fluid is sometimes observed at the operating gas-condensate reservoirs which entails unbalance of the well operation and leads to unstable work of the well. Both external impact of periodic factors and monotonous energy inflows into the system could be the reasons for observed pulsations. The system converts the incoming energy into vibrations due to its nonlinearty. Therefore, investigation of the wave filtration regime, which is discovered during the development of oil and gas-condensate fields, is relevant. The possibility of occurrence of periodic solutions in the filtration process is associated both with the stability loss of stationary solutions of the general two-phase multicomponent filtration equations and with the transformation of the resolving equation for pressure into wave equation with certain combination of numerical values of its parameters. The solution of the wave equation makes it possible to describe mathematically the conditions for the occurrence of such oscillatory flow regimes for a gas-condensate system in a first approximation. The paper focuses on a mathematical description of the wave filtration process, obtainment of the periodic solutions of the isothermal two-phase filtration problem and calculation of the period of these oscillations depending on the parameters characterizing the mixture and the porous medium. It is shown that periodic solutions can be obtained not for any values of these parameters, but only for their certain combination.