Background: Hospitals are the front line of dealing with Incidents. Chemical, biological, radiological, and nuclear (CBRN) incidents are alarming for governments' healthcare providers and the public. Therefore, they must make the necessary preparations to deal with these incidents. Objectives: This study aimed to evaluate the preparedness of hospitals against chemical, biological, radiological, and nuclear incidents and the related influential factors. Methods: The present study was a cross-sectional survey in northwest Iran, 2020-2022. The statistical population was the hospitals of West Azerbaijan province. The inclusion criteria were that hospitals must be university or therapeutic affiliated with the West Azerbaijan University of Medical Sciences, and at least one year had to be passed since the hospital’s operation. Also, the exclusion criteria were that the hospitals were on the verge of closing or changing their use. In this way, 26 hospitals in West Azerbaijan were studied. The "Canadian Center for Emergency Preparedness" evaluation checklist research tool was used to determine the level of preparedness of the studied hospitals in CBRN incidents. The data was collected for 5 months, from January to May 2021. Cronbach's alpha score for this checklist was 0.94. Descriptive and analytical statistics indicators were used for data analysis using SPSS 20 software. Results: The study showed that the hospitals lacked the preparation, capacities, and abilities to deal with CBRN incidents. In the single-variable mode, in the chemical dimension, the number of morgues of the deceased (P = 0.006); in the biological aspect, per capita educational factors in the biological domain (P = 0.03), the number of facility personnel (P = 0.04), the number of infectious disease specialists (P = 0.02), the number of equipment with optimal laboratory capabilities (P = 0.04), and the number of morgues of the deceased (P = 0.006); in the radiological and nuclear dimensions per capita of nuclear education (P = 0.01) and dosimeter (P = 0.03), and the general dimension the CBRN training per capita (P = 0.004), the number of personnel (P = 0.015), and laboratory equipment (P = 0.006) had a significant relationship with the preparedness of hospitals against CBRN incidents (P < 0.05). Conclusions: Overall, this study's results showed that hospitals' preparedness against CBRN incidents was unsatisfactory, and appropriate policies needed to be adopted to improve it.