Background and Aim: A considerable number of pre-hospital emergency technicians have been negatively impacted by occupational fatigue and depression. This research was conducted to examine the effect of rosemary essential oil on the pre-hospital emergency technicians' occupational fatigue and depression. Materials and Methods: Eight pre-hospital emergency stations were randomly chosen in this community trial study. Subsequently, four stations were randomly assigned to the intervention, and four stations were allocated to the placebo groups. 8 to 10 technicians were chosen from each station. In the intervention group, badges with 25% rosemary essential oil and badges impregnated with refined almond oil in the placebo group were used for two hours in 3 shifts per week. The participants completed the fatigue severity scale and the DASS-42 depression subscale before and one hour after the intervention. In this study, chi-square, paired t-test, and independent t-test were used. Results: The statistical analysis indicated no remarkable distinction between the mean occupational fatigue (p=0.17) and depression (p=0.15) scores in the two groups before the intervention. After the intervention, there were no significant differences with regard to the mean and mean changes in occupational fatigue scores between the intervention group and the placebo group (p=0.65). However, in contrast with the placebo group, significant decreases were observed in the mean and mean changes in depression scores in the intervention group one hour after the intervention (p<0.001). Conclusion: Although inhaling a composition of 25% rosemary essential oil does not have any effect on the reduction of occupational fatigue, it can be useful in reducing depression in pre-hospital emergency technicians.