The room temperature phonon modes of the isostructural (Nd,Yb):Y x Gd 1−x (VO 4 ) laser crystals were determined using the Raman scattering technique, and the observed wavenumbers follow the overall mode distribution expected for REVO 4 (RE=rare earth) compounds with the tetragonal zircon structure, D4h19. They were assigned according to the group theory in terms of the internal modes of the VO 4 tetrahedron and the external modes of the Y x Gd 1−x (VO 4 ) lattice. No appreciable changes in the phonon wavenumbers were observed for Yb:GdVO 4 (Yb=0.008, 0.015, 0.020, 0.025, and 0.035), indicating that the force fields in the GdVO 4 lattice are not strongly altered by Yb doping at the Gd site. However, most of the phonon wavenumbers in the systems (Nd,Yb):Y x Gd 1−x (VO 4 ) shifts upwards (one-phonon-like behavior) when Y replaces for Gd.