We describe a simple strictness analyser for purely-functional programs, show how its results are used to improve programs, and provide measurements of the effects of these improvements. These measurements are given both in terms of overall run-time, and in terms of internal operations such as allocations, updates, etc. Despite its simplicity, the analyser handles higher-order functions, and non-flat domains provided they are non-recursive. Ths paper appears in Functional Programming, Glasgow 1993, ed Hammond and O'Donnell, Springer Workshops in Computer Science, 1993, pp201-220. 1 Introduction A lot has been written about strictness analysis for non-strict functional programs, usually in the hope that the results of the analysis can be used to reduce run-time. On the other hand, few papers present measurements of how well it works in practice. Usually, all that is presented are the run-times of a variety of (usually small) programs, with and without strictness analysis enabled (eg Sm..