To evaluate the clinical features, pathological findings, treatment, and prognosis of patients with orbital natural killer/T-cell lymphoma (NKTCL).This retrospective study collected clinical data from 11 patients diagnosed with orbital NKTCL by pathological examination at Beijing Tongren Hospital, Capital Medical University, between November 2005 and March 2024. The patients were followed up to assess their prognosis.The median age of patients with orbital NKTCL was 51 years, with a slight male predominance. All cases were unilateral, with clinical presentations of eyelid or periorbital swelling, and other symptoms including decreased vision (90.9%), conjunctival congestion (90.9%), ocular motility disorders (81.8%), proptosis (63.6%), and ptosis (36.4%). All patients had surrounding tissue involvement, with the most common sites being the eyelid (11 cases), eyeball wall (7 cases), and lacrimal gland (5 cases). Additionally, 63.6% of patients had concurrent soft tissue involvement of the nasal region, while 36.4% had isolated orbital NKTCL. Pathological examination revealed diffuse proliferation and infiltration of atypical lymphocytes, occasionally with necrosis. Immunohistochemical staining showed positive expression of GrB (11 cases), CD3 (10 cases), TIA1 (9 cases), CD56 (8 cases), and EBV/EBER (10 cases). All patients underwent ocular surgery, 7 received postoperative chemotherapy, and one received concurrent local radiotherapy. Follow-up (median duration: 120 months) revealed poor prognosis, with 5 patients lost to follow-up, 5 deaths, and only one survival without recurrence.Orbital NKTCL is highly aggressive, rapidly progressive, and has a poor prognosis. Its clinical symptoms are similar to orbital cellulitis or inflammatory pseudotumor. When anti-inflammatory and corticosteroid therapies prove ineffective, early biopsy for histopathological confirmation is strongly recommended. Upon diagnosis, prompt chemotherapy and radiotherapy should be initiated to improve the patient's prognosis.© 2025. The Author(s).