Background and Purpose: Nausea is a side effect of some diagnostic techniques, one of which is diagnostic-therapeutic endoscopy. This complication occurs after the procedure and is annoying for the patient. Chamomile is a herb with anti-nausea properties in traditional medicine. This study was conducted with the aim of investigating the effect of chamomile inhalation on nausea after endoscopy. Materials and Methods: This study is a single-blind randomized trial with a population of 160 participants in two intervention and control groups, sampled in June 2017 at Vasei Sabzevar Hospital. After examining inclusion and exclusion criteria, the informed consent form and demographic information were completed by the patient, and then aromatherapy was performed for 20 minutes before endoscopy. Immediately after the endoscopy, nausea was measured using the VAS scale. Data analysis was performed using SPSS21 software and Chi-2, Fisher, Kolmogrof-Smirnov and t-test statistical tests. Results: Most of the participants in this study were women, unemployed, and urban residents. The average age of the entire population was 42. 10. The average score of nausea after endoscopy was 5. 27±, 2. 22 in the intervention group and 5. 93±, 2. 31 in the control group, which did not have a statistically significant difference (p=0. 67). Conclusion: The results of this study showed that inhalation of chamomile essential oil is not effective in reducing nausea after endoscopy.