1. Rock creep is an unfavorable factor leading to a considerable increase of tensile stresses in a pressuretunnel lining. On the contrary, concrete creep leads to a decrease of tensile stresses in the lining, but the practical use of this circumstance is possible only under conditions of a gradual increase of tunnel pressure to the operating pressure. 2. We see from an analysis of the solution obtained that, depending on the relationship of the creep parameters of the concrete and rock, the character of change of stress in the lining with time can vary substantially. The maximum stress must be established on the basis of a special analysis. Under certain conditions a gradual increase of tunnel pressure leads to a considerable decrease of the maximum stress in the lining. 3. It is recommended to make the lining of pressure tunnels of concrete having a high creep accompanying gradual increase of the pressure in the tunnel. The construction of a lining from such concrete will greatly lessen the adverse effect of rock creep and will make it possible to obtain economic designs of high-pressure tunnels of modern hydroelectric stations.