Background: Hemodynamic changes are among the side effects of diagnostic cardiovascular procedures. Hypothesizing that the anxiolytic effects of lavender oil inhalation could alleviate anxiety among patients undergoing diagnostic cardiovascular modalities, we conducted the present study on patients undergoing coronary angiography with the aim of assessing the effects of lavender oil inhalation on hemodynamic changes. Method: This clinical trial enrolled 80 patients hospitalized for coronary angiography. The patients were randomly divided into 2 groups: the lavender group (n = 40), who inhaled lavender oil during angiography, and the control group (n = 40), who received only 1 mg of lorazepam on the night before the procedure (similar to the lavender group). Demographic data and hemodynamic variables (blood pressure and heart rate) were recorded in all the patients before and after lavender oil aromatherapy. Results: Demographic parameters had no statistically significant differences between the 2 groups (P > 0.05). After lavender oil aromatherapy, hemodynamic parameters such as systolic and diastolic blood pressures and heart rate were significantly reduced (within normal ranges) in the intervention group by comparison with the control group (P ≤ 0.05). Conclusions: By reducing the stress response, lavender oil inhalation had efficacy in controlling blood pressure and heart rate in our patients undergoing coronary angiography. (Iranian Heart Journal 2017; 18(4):29-33)