The objective of this study was to develop a modern version of the paediatric injury pyramid, a visual classification of injury severity, and to present mechanism-based pyramids. As the original paediatric injury pyramid was described in 1980, the injury epidemiology from 1980 was compared with 2004. Comprehensive emergency department, hospital discharge and death data for Massachusetts in 2004 were used to determine injury rates for residents aged 0-19 years. Injury pyramids were constructed on the basis of the number of injuries resulting in death, hospitalisations and emergency department visits. In 2004, unintentional and intentional injuries accounted for 197 deaths, 7120 hospitalisations and 199,814 emergency department visits giving a ratio of 1:36:1014. The 2004 injury pyramids differed by mechanism and intent. Compared with 1980, there were lower rates for overall injury and for most major injury mechanisms in Massachusetts in 2004.