The aim of this study was to provide normative data for performance on the 20 m shuttle-run test of cardiorespiratory fitness in English schoolchildren. A total of 7366 10-16 year olds completed the 20 m shuttle-run test. We expressed performance as the number of shuttles completed, test score (shuttles and levels) and estimated peak oxygen consumption (VO2peak). We calculated descriptive statistics for each age-sex group to construct percentile curves and tables. To assess the cardiorespiratory fitness of our sample, we calculated the number of participants who fell below proposed cut-offs for low cardiorespiratory fitness based on either completed shuttles or VdotO2peak. These cut-offs did not agree in terms of frequency of classification. The classification based on estimated VO2peak suggested low fitness was more prevalent in males and that the incidence of low fitness increased with age in both sexes. These are the first normative data for shuttle-run performance in English youth and can now be used to interpret data from this cardiorespiratory fitness test. The two cut-offs used for low fitness did not agree and future research should establish a cut-off for test performance which can predict present or future ill-health.