Equilibrium phase relationships in the NbTiZr system are computed using the Calphad approach. SGTE-recommended lattice stability expressions for the pure elements are used. The thermodynamic model parameters for NbTi and NbZr are taken from recent assessments. A new thermodynamic description of TiZr is obtained by optimizing available experimental thermochemical and phase diagram data. Phase diagrams of the three limiting binaries, liquidus projection, solidus projection and a number of isothermal sections are computed.