Encapsulating peritoneal sclerosis (EPS) is a serious complication of peritoneal dialysis (PD). Patients with EPS showed 25-55% mortality rate, but the optimal treatment for EPS is not clear. EPS treated with tamoxifen is associated with lower mortality, but other studies showed no difference in outcome. This study aimed to evaluate the clinical outcomes of EPS treated with tamoxifen in end-stage kidney disease patients. We conducted a 20-year (from January 2004 to December 2023) retrospective observational study. We included 34 EPS patients (aged 59.0 ± 11.7 years, male:55.9%) diagnosed with abdominal computed tomography and treated with tamoxifen in Dong-A university hospital. We also analyzed data according to 10-year period (period 1:2004-2013, n=24, period 2: 2014-2023, n=10). The mean duration of PD before diagnosis of EPS was 79.0 ± 45.0 months (range 27-192). Four patients had treated with hemodialysis prior to diagnosis of EPS. The length of hospital stay was 40.1 ± 28.4 days at the time of diagnosis and the survival time was 32.0 ± 32.2 months. Prescribed dose of tamoxifen was 22.3 ± 7.4 mg and prescribed days were 106.6 ± 172.1 (range 5-880). Four patients were also treated with low dose prednisone and five patients were treated with tamoxifen over 5 months. The length of hospital stay was shorter at period 2 compared to period 1 (26.0 ± 18.2 vs. 46.0 ± 30.1). Four patients required surgical treatment and one patient died after surgery. The peritoneal culture at diagnosis of EPS showed fungus (32.4%), no growth (29.4%) and gram-negative bacteria (26.5%). The overall mortality rate was 14.7%. No adverse reaction related with tamoxifen was found. Tamoxifen may be safe and essential for EPS treatment in patients with PD treatment history. Further studies are necessary to evaluate the effectiveness of long term treatment with tamoxifen.