Police and health authorities play an essential role in road traffic injury (RTIs) surveillance, prevention and control. Appropriate reporting of RTI by both authorities can help in adapting local injury prevention policies. This study aimed to compare police- and health authority-based surveillance systems of RTI in Mongolia. The study setting was Ulaanbaatar, the capital city of Mongolia accounting for 43% of the Mongolian population. This descriptive study combined interviews with key informants (n=30), statistical reports and direct observations. Surveillance data from 2008-2010 was analysed using frequency tables. We concluded that police underreported RTI and fatalities compared to health authorities, and therefore information about local RTI factors was not adequately collected and used by the current system. Linking both datasets seemed feasible because of identifiers and other comparable information available in both of them. This could increase the utility of RTI information captured by both authorities for making prevention policies. Nevertheless, both surveillance systems might require improvements in reporting of crash circumstances to assist future preventive efforts.