BACKGROUND/AIM: CD38 is a cell surface marker commonly present in plasma cells and activated T cells, while CD138 is a representative plasma cell marker. The aim of this study was to describe the expression of cell surface markers including CD38 and CD138, in the tumors of patients with IgG4-related ophthalmic disease (IgG4-ROD) and extranodal marginal zone B-cell lymphoma (EMZL) of the ocular adnexa. MATERIALS AND METHODS: Twenty-four consecutive patients of whom 12 had IgG4-ROD and 12 EMZL were enrolled in this study. Medical records were reviewed for flow cytometry (FCM) results on conventional T-cell markers, B-cell markers, CD38 and CD138. RESULTS: Positive rates of T-cell markers, CD38 and CD138 were significantly higher in IgG4-ROD than in EMZL (p<0.01 and p<0.05, respectively). CONCLUSION: Our FCM results on CD38 and CD138 showed that the lymphocyte populations were different between IgG4-ROD and EMZL, which may reflect the different pathophysiology of the two diseases.