Aim. This study was conducted to evaluate the effect of aromatherapy on ICU nurses' stress.

Background. Nursing, due to its high sensitivity, is known as one of the most stressful professions. ICU nurses experience more stress than other nurses. This stress can reduce the quality of patient care and results in nurses' feelings of inadequacy and depression. Aromatherapy, as a method of complementary medicine may reduce anxiety and warring.

Method: This was a quasi-experimental study in which 70 nurses, working in intensive care unit, were divided into experimental and control groups. Nurses' stress were measured before intervention, then intervention (inhalation of Lavendula using tags for 4 consecutive shifts, each shift for 20 minutes) was was applied for the experimental group (control group received no intervention). At the end of intervention in experimental group, the stress was again measured in both groups. Data were analyzed using the Chi-square and t-test in the SPSS, version 20.

Findings. After intervention, the mean of stress in experimental group (20.57±4.20) was not statistically different when compared with control group (22.43±5/24). But, in the experimental group, the mean of stress score after intervention (20.57±4.20) was significantly lower than the mean of stress score before intervention (22.32±4.61) (P=0/001). Comparing the groups, the changes in mean stress score before and after the intervention was statistically significant (P=0.001).

Conclusion: The findings of this study showed that the Lavender essence can reduce stress in ICU nurses. It is recommended that the aroma of lavender be applied to reduce stress in ICU nurses.