Lymphoid infiltrates in the ocular adnexa are mostly low-grade B-cell lymphoma, but their clinicopathologic characteristics and prognostic factors have not been extensively analyzed according to the Revised European-American Lymphoma (REAL) Classification. We reviewed histopathologic sections from 77 patients with primary ocular adnexal lymphoid infiltrates, and conducted univariate and multivariate analyses of possible prognostic factors. Fifty-seven of the 77 patients were confirmed to have malignant lymphoma. Histopathologic sections from 44 of the 57 patients were reclassified into the following categories; marginal zone lymphoma (MZL) in 35, mantle cell lymphoma (MCL) in two, diffuse large cell lymphoma (DLCL) in six, and lymphoplasmacytoid lymphoma (LPL) in one. In the remaining 13 patients, biopsied specimens were inadequate for further subclassification. The cause-specific survival rates of the 57 patients with primary ocular adnexal lymphoma at 5, 10, and 15 years were 90.1%, 84.8% and 84.8%, respectively. The univariate analysis showed that the clinical stage, serum lactate dehydrogenase (LDH) value and histopathologic subtype were significant. The 5-year cause-specific survival rate of the 35 patients with MZL was 100%, whereas that of the eight patients with non-MZL (DLCL and MCL) was 25% (p<0.0001). The multivariate analysis revealed that the histologic subtype (p=0.010) and serum LDH value (p=0.015) were independent significant predictors of survival. We conclude that malignant lymphomas occurring in the ocular adnexa histologically consist mostly of MZL. The histologic subtype according to the REAL Classification significantly predicts the prognosis of ocular adnexal lymphoma.