The phonon properties of Zn1-xMxSe1-yTey quaternary alloys grown on GaAs(1 0 0) and ZnTe(1 0 0) substrates by molecular beam epitaxy have been studied by Raman scattering. ZnSeTe- and MgSeTe-like longitudinal optical phonon modes and ZnSeTe-like transverse optical phonon mode were observed in the room-temperature Raman spectra. The Raman scattering in Zn1-xMexSe1-yTey quaternary alloys exhibits a two-mode behavior.