Objective: Describe the knowledge and practice of self-care among patients with post-operative of the lower third molar at the Air Defense – Air Force Academy and related factors. Participants and methods: A cross-sectional descriptive study on 99 patients with post-operative of the lower third molar treated as outpatients at Dental Center 225, Air Defense – Air Force Academy from December 2021 to June 2022. Results: The percentage of patients with post-operative of the lower third molar accounted 80.8%, and 66.7% for self-care knowledge and practice.. The study initially identified the related factors of female patients with a history of first surgery had better knowledge. The patients with high education and good social support had better self-care practice. Patients with self-care knowledge achieved self-care practice 6.5 times higher than those with low self-care knowledge. Conclusion: The patient had good knowledge of self-care for post-operative of the lower third molar of lower jaw. The patients had the right knowledge and the practice had good treatment results. Thereby contributing to improving the patient’s attitude and behavior in the implementation of self-care for post-operative of the lower third molar.