Background: Lavender proved to be effective in relieving pain arising from many conditions. However, there is a paucity of studies addressing its effectiveness in the relief of post-cesarean section (CS) pain. Aim: to investigate the effectiveness of inhalation of Lavender oil in relieving post-CS pain. Subjects and methods: This quasi-experimental controlled study was carried at the Postpartum Unit affiliated to Suez-Canal University Hospitals on a convenience sample of 100 postpartum women delivered by CS. They were randomly divided into two equal groups, 50 receiving Lavender oil and oxygen, and 50 control. An interview questionnaire sheet with the Visual Analogue Scale (VAS), and the Modified Version of Johansson Pain-O-Meter (MJPOM) pain scale was used to collect data. The work was from October 2013 to January 2014. Results: Women in the two groups had similar demographic and obstetric characteristics. The mean VAS pain score was almost double in the control group compared with the study group (p<0.001). Moreover, the mean MJPOM pain scores (sensory, affective, and total) were all higher in the control group (p<0.001). Pain scores were higher among primiparas (p<0.001), and 68.0% of study group women reported that Lavender was effective in decreasing their post-CS pain. Conclusion and recommendations: Lavender oil inhalation is effective in relieving post-CS pain. A duplication of this study using a full randomized clinical trial design is recommended to provide a stronger evidence of its effectiveness and to overcome the limitations of the quasi-experimental design concerning internal validity.