ABSTRACT: This study investigated the treatment efficacy and long-term adverse effects of various treatment modalities for primary ocular adnexal lymphomas (POALs). We retrospectively reviewed 107 patients who received first-line chemotherapy, radiotherapy, and other treatment modalities from 1990 to 2015. Nighty-three (87%) patients were diagnosed with mucosa-associated lymphoid tissue (MALT) lymphoma, with the orbit being the most common site (49 patients, 46%). Among 91 patients with stage I-IIE1 disease, 26 underwent chemotherapy, 34 underwent radiotherapy, and 31 received other treatment modalities. For chemotherapy, radiotherapy, and other treatment modalities, the 5-year event-free survival (EFS) rates were 90.0%, 89.7%, and 85.8% and the 5-year overall survival (OS) rates were 100%, 90.4%, and 87.5%, respectively. Moreover, among 80 patients with stage I-IIE1 MALT lymphoma, the complete remission, 5-year EFS and OS rates were not significantly different between patients receiving chemotherapy and those receiving radiotherapy. Among 16 patients with stage IIE2-IVE disease, the 5-year EFS rates for chemotherapy alone (n = 11) and combined radiotherapy and chemotherapy (n = 5) were 61.7% and 80%, respectively, whereas the 5-year OS rate for both groups was 80.0%. Neutropenia (15.2%) was the most common side effect in patients who received chemotherapy, whereas cataract (16.3%) was the most common late sequela in patients who received radiotherapy. Multivariate analysis revealed that old age (> 60 y) and an advanced stage (stage III/IV) were prognostic factors for poor OS. Our results indicate that chemotherapy yields satisfactory disease control and fewer side effects, and acts as an alternative therapy for patients with localized POALs.