Deformation behavior of Zr-Nb alloys under uniaxial compression, accompanied by phase transformations, is considered by the example of Zr-1%Nb and Zr-2.5%Nb alloys. Model samples were deformed at temperatures of β- and (α+β)-regions of the phase diagram Zr-Nb. Mechanisms, responsible for plastic deformation of alloys by different temperature-rate regimes, were determined on the basis of textures, arising in deformed samples. Among these mechanisms there are crystallographic slip in grains of β-Zr and α-Zr as well as mutual displacements of crystallites along interphase boundaries. The latter mechanism sharply intensifies under conditions of α↔β phase transformations and lies in the basis of superplasticity. An input of each mechanism into plastic deformation of material depends on the temperature-rate regime of compression and determines its anisotropy.