Background: Slow Deep Breathing (SDB) is a breathing technique with deep breathing frequency in a long phase of exhalation. Slow Deep Breathing can increase and decrease the supply of oxygen to the brain so that oxygen metabolism in the brain increases. Objective: To determine the effect of Slow Deep Breathing on decreasing pain and anxiety levels in Sleman Yogyakarta Hospital. Methods: This study uses a quasy-experimental design with the type of pre-post test without control group design. Research sample of 31 respondents. Sample measurement is done by accidental sampling. Wilcoxon test was used to determine pain and paried t test to determine the level of anxiety Results: There was a significant effect of Slow Deep Breathing administration on decreasing pain and anxiety with a p-value of 0.001. Conclusion: Slow Deep Breathing (SDB) can be applied in the handling of patients with pain and anxiety in RSUD Sleman Yogyakarta especially in patients post op appendectomy Keywords: Slow Deep Breathing, Appendectomy, Pain, and Anxiety