Extranodal NK/T-cell lymphoma, nasal type (ENKTCL-NT), is a malignancy derived from NK or T-cell lines, characterized by vascular damage, extensive necrosis, a cytotoxic phenotype, and association with Epstein-Barr virus (EBV). This aggressive tumor presents severe clinical symptoms and is marked by high morbidity and mortality rates. Despite a well-understood pathogenesis, the mortality rate remains high. The tumor microenvironment (TME) plays a crucial role in the disease's pathogenesis and progression, with Treg cells expressing anti-FOXP3 markers being a significant component.This observational study, utilizing a case series design, was conducted with a total sample of 16 paraffin blocks from NKTCL-NT patients registered at Dr. Mohammad Hoesin General Hospital (RSMH) Palembang, from January 2018 to December 31, 2023, who met the inclusion and exclusion criteria. Anti-FOXP3 antibody was applied to all samples.Patients with ENKTCL-NT were predominantly male (68.75%), while females constituted 31.25%. The age range of the subjects was 14-40 years, with the majority (62.5%) falling within the third to fourth decades of life. The most common anemia status observed was moderate anemia (46.15%), followed by mild anemia (38.46%). The early stage of the disease was the most frequent (66.67%). The population of subjects with high and low FOXP3 expression was equally distributed at 50% each.Subjects with a high density of FOXP3-expressing cells were more commonly found in patients with early-stage disease and those with mild to moderate anemia status.