Background: Studies have shown that aromatherapy improve health problems related to anxiety, depression, heart rate variability (HRV), and sleep. However, the effect of aromatherapy in women who suffer from menopausal syndrome and its specific effects on HRV and sleep quality are unknown. Purpose: This study designed an aromatherapy intervention and evaluated its effect on menopausal syndrome, HRV, and sleep quality in women. Methods: This double-blinded randomized controlled trial was conducted at a medical center hospital. A total of 84 participants who met the study criteria were randomly assigned using permuted block randomization. The experimental group received a 20-min inhalation of essential oil and the control group received a 20-min inhalation of sweet almond oil every night for 4 weeks. Posttest data was collected at 2 weeks after completion of the intervention. Data were collected using the Green Menopausal Symptom Scale, HRV device, and Pittsburgh Sleep Quality Index. Results: After adjusting for age, the results of the generalized estimation equations (GEE) showed that all outcomes were significantly different in both the experimental group and the control group (p <.05) for the interaction effect of group and time, and that the outcome of sleep quality on the 2nd week in the control group was not significantly different (p =.066). Conclusions/ Implications for Practice: This study supports that the 4-week aromatherapy intervention improves menopausal symptoms, the activity of autonomic nervous systems, and sleep quality in women with no adverse side effects. In the future, this intervention may be applied in outpatient departments to promote the health of menopausal women.