This quasi-experimental study was to explore the effects of back massage with Lavender essence oil on the stress response of the ICU nurses. Method: Twenty nurses were selected as an experimental group and twenty nurses were in the control group. Lavender essence oil mixed with Jojova carrier oil was used to massage the neck, shoulder, back, and low back. Massage was done three times a week for 20 minutes for 2 weeks by the massage therapist. The stress response was measured with a subjective stress score, Cortisol and IgA level in saliva. The cortisol level in saliva was analyzed by an radioimmunoassay before and after back massage. The level of IgA in saliva was analyzed by an immunoturbidimeter assay and subjective stress scores was measured by Visual Analogue Scale. The data was analyzed using SPSS 8.0 and the hypotheses were tested by ANCOVA and the Pearson coefficient correlation. Result: 1) Score of subjective stress decreased significantly after the use of back massage with Lavender essence oil. 2) Level of Cortisol in saliva did not change significantly after the use of back massage with Lavender essence oil. 3) Level of IgA in saliva increased significantly after the use of back massage with Lavender essence oil. 4) After the use of back massage with Lavender essence oil, there was significant negative correlation between subjective stress and level of IgA in saliva. Conclusion: Back massage with Lavender essence oil is an effective intervention to reduce the stress response in the ICU nurses.