Introduction: Pain is one of the main and unavoidable stages of labor. The purpose of this study was to compare the effects of entonex gas and aromatherapy with lavender on the severity of labor pain. Methods:The present study was a double-blind randomized controlled trial with random allocation on 60 nuliparos women in Sanandaj-Kurdistan Be'sat hospital. The intervention was performed in two groups of 30 in active phase of labor. In the Entonox group, Entonux gas was smelled by the mother in contractions. In the lavender group, aromatherapy with lavender was performed in contractions. The severity of pain was measured in dilatations of 4-5, 6-7, 8-9, and 10 cm before and after the intervention with vas instrument. Results:The severity of pain before and after intervention was significantly different in each group (p<0.05). The severity of pain was significant between the two groups in dilatations of 8-9 and 10 cm. After intervention, the mean pain severity in the Entonox group was 6.8 in dilatations of 8-9 cm and 8.3 in the lavender group (p<0.05). Also it was 7.7 in dilatation of 10 cm in Entonox group and 8.9 in lavender group (p<0.05). Entonux gas significantly increased maternal complications including mouth dryness, dizziness, nausea, and headache (p<0.05). Conclusion:The present study showed that Entonox gas and aromatherapy with lavender both can reduce the severity of labor pain. But the effect of Entonux gas is greater in reducing labor pain than lavender.