By measuring the sensitive salivary endocrinological stress markers cortisol and chromogranin A (CgA), we investigated effects on stress of lavender and peppermint aromas. Groups of volunteers were each exposed to an airborne organic essential oil: either lavender or peppermint or, for control, odourless jojoba. Saliva samples were collected immediately before and after the 10-min exposure and 5 and 10 min later. Salivary cortisol and CgA levels were evaluated by enzyme-linked immunosorbent assay. After exposure, in the peppermint aroma group, salivary cortisol statistically significantly decreased and salivary CgA statistically significantly increased. No similar changes were found in either the lavender aroma or the control group. These findings suggest that peppermint aroma may be useful for relieving stress.