The article presents a review of foreign literary sources over the past few years relating to problems of lifetime estimation, diagnostics of turbine damage, optimization of operation modes and planning of repair works for ensuring trouble-free operation of units. The damages, typical for equipment after long operation, have a fatigue nature that is confirmed by the analysis of causes of several accidents at foreign hydroelectric power stations described in open sources of information. Particular attention is paid to the impact on the lifetimes of off-design operating conditions of hydraulic units, taking into account the constructive and technological stress concentrators, appearance and growth of defects (cracks). The article presents the methods currently used for stress-strain estimation of the most important turbine components as one of the main stages of lifetime estimation, the features and problems of their practical application, which are determined by typical operating conditions, technical and financial capabilities. The review highlights the main tendencies in developing the approaches to the problem of lifetime estimation of hydraulic equipment which determined by the highest modern requirements to the conditions of using the hydropower generation capacities. The established English abbreviations, concepts and terms relating to matters covered in this paper are given in the text. The possibility and feasibility of using foreign experience for lifetime estimation of Russian hydroelectric equipment outside the design lifetime are assessed based on the analysis of the publications discussed in this review. The prospects for developing the approaches to lifetime estimation of hydro turbines in the near future are also presented.