This review has been prompted by concerns and anecdotal stories about low levels of fitness amongst today's young people and the possible consequences of this for their current and future health. Solutions to the "problem" have included proposals to fitness test children and to use this information to improve their health status. While there is no doubt that young people's health and fitness are important issues, the authors consider it equally important that policy-makers and practitioners work from an informed base in order that any actions taken are relevant, meaningful and effective. This article summarizes the literature on children's fitness testing which was reviewed as part of a feasibility study commissioned by the National Assembly for Wales conducted between October 2003 and March 2004. The specific aim of the study was to determine if there was a need and whether it was cost effective and practical to carry out a research project investigating the fitness levels of Welsh children. A key aspect of the methodology included a comprehensive review of the relevant literature to establish the key findings and issues associated with the fitness testing of children. A worldwide literature search (of papers published in the English language) was carried out using metalib (a multi-database research tool). This article focuses only on the main and consistent findings, trends and issues associated with: physical fitness and the associated health benefits in children, the physical fitness status of children, monitoring children's physical fitness, and the role of children's fitness testing in physical activity and fitness promotion. (Contains 1 table.)