Prepared by the Subcommittee on Uncertainty and Reliability Analyses in Design of Hydraulic Structures of the Technical Committee on Probabilistic Approaches to Hydraulics of ASCE. This report contains 13 papers presenting the application of reliability analysis to the design and safety of hydraulic structures. Several recent major failures of engineering systems have raised public concern on the safety and reliability of engineering struct.ures. Decades ago, a quantitative evaluation of the reliability of structures was not possible and engineers used safety factors that were determined mainly through experience and judgement. Recent advances in probability methods and computers make it feasible to evaluate the contributions of various technologic and natural factors to the safety and reliability of structures.ØThe first four papers in this report discuss techniques pertinent to reliability and uncertainty analyses. The next nine papers explore how these techniques can be applied to dam safety, coastal floods, and hydraulic structures. The report concludes with a reprint of an article by Vrijling on the Eastern Scheldt Storm Surge Barrier of the Delta Project in the Netherlands and the use of reliability analysis for sewer design.