NERF is a computer program which evaluates time histories of reliability functions representing the aggregated fatigue behaviour of a population of structures or components which possibly contain a crack at the location being studied. Given data describing the mean rate of fatigue crack growth and resultant strength degradation together with a statistical description of the applied load sequence and population variations about the mean, NERF computes, among other functions the risk rate and probabilities of failure and survival. An important and useful facility of the program is that it allows for the effects of various inspection strategies and can be used as a development tool in selecting the best strategy for a particular population of structures. This document details the reliability models that can be evaluated by NERF, the use of the NERF sui! te of programs, the definition of input data, the operating instructions (including interactive dialogues) and the various result produced. examples, complete with the associated input data and specimen results are also presented. Keywords: Risk analysis; Fortran; Probability density functions; Numerical integration; and Australia.