We develop a method for the evaluation of the rate of delayed hydride cracking in zirconium alloys. The model is based on the stationary solution of the phenomenological diffusion equation and the detailed analysis of the distribution of hydrostatic stresses in the plane of a sharp tensile crack. The rate of delayed hydride cracking in reactor tubes made of Zr–2.5% Nb alloy is found both theoretically and experimentally. It is shown that the theoretical results are in good agreement with the experimental data.