Abstract Introduction: Labour pain is a main preoccupation of pregnant women. In this study, the authors determined the effect of lavender aromatherapy on pain intensity perception and intrapartum outcome in primiparous women. Methods: In this randomised controlled trial, 160 participants were divided into two groups. The aroma group received 0.1ml of lavender essential oil mixed with 1ml of distilled water via tissues attached to their gowns close to their nostrils. Meanwhile, the control group received 2ml of distilled water in a similar way. Pain intensity perception was measured by Visual Analogue Scale (VAS) before the intervention and at 30 and 60 minutes afterwards. Results: The mean of pain intensity perception in the aroma group was lower than that of the control group at 30 and 60 minutes after the intervention (p