Background The objective of this study is to determine the association between Chile's 2005 child restraint legislation (CRL) and the incidence of severe paediatric motor vehicle-related injury.

Methods We analysed motor vehicle injury data from Chile's Road Safety Commission from 2000 to 2012 to determine the association between Chile's 2005 CRL and severe paediatric injury. Using Poisson time-series models we assessed the effect of the law on two outcome variables: (1) severely injured children per vehicle fleet; and (2) severely injured children per population.

Results Chile's 2005 CRL is significantly associated with a 24% reduction in severely injured children per vehicle, and 19% reduction in severely injured children per population in the 1st year of its enactment. In 2007 this law is also significantly associated with a 17% decrease in severely injured children per vehicle, and with an 11% decrease in severely injured children per population. However, this legislation had a short-term effect since no reductions in severely injured children per vehicle were observed after 2009 and no reductions for severely injured children per population were registered after 2008.

Conclusions This is the first study to examine the association between CRL and severe paediatric injury in a Latin-American country. This study suggests that Chile's CRL was only effective in the short term. To support this type of reforms in the long term, other measures such as police enforcement, public information campaigns and involvement of public health professionals in educating parents about the benefits of using child restraints should be considered.