Background & Aims: Labor conditions cause stress and anxiety specifically in nulliparous women and hence the chance of a normal vaginal delivery is reduced. According to some studies lavender scent improves mood and reduces stress and anxiety. The purpose of this study was to investigate the effect of lavender scent on anxiety status in nulliparous women and also to determine changes in plasma cortisol, serotonin and 5- hydroxyl indol acetic acid (5-HIAA) concentrations. Methods: In this study 121 nulliparous women with gestational age >37 weeks and cervical dilatation of 3-4 cm, referring to labor room of Zeinabieh and Hafez hospitals in Shiraz were devided into case group (N=63) and control group (N=58). The case group smelled lavender essential oil for 1 hour. In both groups anxiety changes were determined before and after aromatherapy by Spielberger questionnaire, and at the same times pulse rate, blood pressure and plasma cortisol, serotonin, and 5-HIAA concentrations were determined by ELISA. Results: Anxiety status and hormone levels were the same in both groups at the beginning of the experiment. Lavender decreased significantly anxiety and cortisol concentration while increased plasma serotonin and 5-HIAA concentrations. The difference between cortisol concentration before and after the aromatherapy in the test group was significantly lower than that of the control group. Lavender scent did not affect blood pressure and pulse. Conclusion: Aromatherapy with lavender improves anxiety status during labor in nulliparous women and decreases cortisol secretion from adrenal gland and increases serotonin secretion from GI tract.