Background: Nephrolithiasis is a urological disorder characterized by the formation of kidney stones due to the deposition of crystals and organic matrix in the urine. Pyelolithotomy is often performed for large kidney stones, but it can cause postoperative pain that interferes with patient mobility, rest, and recovery. Purpose: To describe the application of deep breathing relaxation techniques to reduce pain in patients with post-pyelolithotomy nephrolithiasis. Method: This was a descriptive case study using a nursing care approach. The subject was Mrs. S, 58, who was hospitalized in the Al-A'raaf Ward at PKU Muhammadiyah Bantul General Hospital. Data were collected through interviews, observations, physical examinations, and medical record reviews. The intervention consisted of deep breathing relaxation techniques for 10–15 minutes, three times daily for three days, accompanied by pharmacological therapy with ketorolac. Pain levels were measured using the Numeric Rating Scale (NRS). Results: Patients experiencing acute postoperative pain with an NRS score of 4 appeared grimacing, restless, and restricted movement. After three days of intervention, the pain scale gradually decreased to NRS 1. The patient appeared more relaxed and comfortable, able to perform light mobilization, and experienced improved rest quality. Conclusion: Deep breathing relaxation techniques effectively help reduce pain intensity in patients with post-pyelolithotomy nephrolithiasis and can be used as a complementary therapy in postoperative pain management. Keywords: Deep Breath; Nephrolithiasis; Pheyelitotomy.