BACKGROUND: EMS providers are often the only emergency workers with medical knowledge at the scene of chemical hazards and are exposed to severe risks. They should always be prepared to face chemical hazards to be able to provide an effective response to them. Therefore, this study identified the dimensions and components of emergency medical services system preparedness in chemical hazards. METHODS: We searched the relevant electronic databases, including ProQuest, Embase, PubMed, Web of Science, and Scopus. The search included articles in English published up to November 2, 2023. In addition, organizational websites, including WHO, CDC, OSHA, NIOSH, FEMA, IFRC, NFPA, OECD, and OPCW, were searched to find gray literature. Studies were selected using the PRISMA checklist, and thematic analysis was used to analyze the findings. RESULTS: Finally, of 8193 selected records, 16 papers were included in the final analysis. Using thematic analysis, two main themes, 15 categories, and 57 subcategories were revealed. The categories for management measures included Plans and guidelines, Communication and coordination, Risk management, Management of physical spaces and Sources of funding, and for technical measures were recognition of chemical release, incident scene management, personal protection, casualty management, ambulance equipment and drugs, decontamination, psychological support, supporting units, Chemical, Biological, Radiological, Nuclear, and Explosives (CBRNE) ambulances, and training. CONCLUSIONS: Due to the importance and extent of the effects of chemical hazards, EMS systems need to develop their preparedness using more specific approaches to provide medical services in chemical hazards. EMS systems should provide medical equipment and antidotes, chemical ambulances, chemical protective equipment, and necessary physical spaces with appropriate financing. Also, preparedness and response plans should be prepared and practiced regularly based on previous lessons learned and with the cooperation and participation of other organizations involved in chemical disasters.