Propagation of plane elastic waves in an infinite porous medium containing two immiscible fluids has been investigated. Four plane waves can propagate with distinct phase speeds in such a medium. Out of these four waves-three are compressional waves and one is transverse wave. Out of these four waves, two compressional waves and one transverse wave are the same waves earlier encountered by Biot in the porous medium saturated by single fluid. The appearance of the third compressional wave is new and arises due to the presence of second fluid in the medium. Using potential method, reflection and transmission of plane waves is studied at elastic/porous and porous/porous plane interface. The effect of inertial coupling is noticed on the reflection/transmission coefficients at elastic/porous interface.The possibility of plane wave propagation has also been studied in fractured porous medium containing two immiscible fluids. The reflection/transmission phenomena are also investigated at...