INTRODUCTION: According to the official statistics, a high rate of road traffic deaths occurs during the transportation of the injured and in medical centers. The way of transporting the injured to the medical centers, the standard time of dispatch and timely treatment in the hospitals, the land use planning of medical centers and rehabilitation are the three missing links of the post-event phase. Therefore, the researchers aimed to assess the effect of rescue and relief services on the severity of traffic accidents in this study.
METHODS: This applied research was conducted based on an exploratory mixed method. The statistical population in the qualitative section included Amin Police Academy professors, experts of both Red Crescent Society (RCS) of Tehran province and Tehran Emergency Medical Service (EMS), who were selected via purposive sampling method. In the qualitative section, the theme analysis method was used and analyzed by using Maxqda-2020 software. The statistical population of the quantitative part included excellent accident experts of 28 districts of Tehran and experts of the RCS and EMS of Tehran province in a stratified random method. In the following, confirmatory factor analysis using structural equation modeling method was used and analyzed with SmartPLS3 software. 
FINDINGS: The dimensions of the impact of rescue and relief services on the severity of traffic accidents from the perspective of Red Crescent Society and Emergency Medical Services experts included equipment (31.077), land use planning (25.610), expertise (23.598), and education (8.243). The most marked impact was related to equipment, and the least impact pertained to education. Furthermore, the dimensions of the effect of rescue and relief services on the severity of traffic accidents from the perspective of accident experts included equipment (42.009), land use planning (34.419), education (33.770), and expertise (8.951). The greatest impact was related to equipment, and the least effect pertained to expertise. In addition, the factor loadings of all dimensions were more than 0.5 being significant at the 0.95 level.
CONCLUSION: Strengthening and developing equipment, land use planning balanced with the geography of missions, and continuous specialized training of rescue and relief of RCS and EMS experts will positively reduce the severity of traffic accidents in the country.