According to a previous review, multiple mucosa-associated lymphoid tissue (MALT)-organs involving marginal zone B cell lymphomas (MZLs) are present in 10-30% of patients. However, the clinical features and specific relationships among involved organs are yet to be clearly identified. In this study, we conducted retrospective analyses of multiple MALT organs involving MZLs (MM-MZLs) to identify their clinical features, treatment, prognosis, and specific relationships among involved organs. For analysis, between June 1987 and June 2009, a total of 55 patients from 17 different institutions in Korea, all of whom were histologically diagnosed with MM-MZL, were included in this study. MM-MZL was defined as MZL involving more than 2 different MALT organs. Multiple involvements within one MALT organ (e.g. both side ocular lesions, multiple lung nodules, and multiple stomach lesions, etc.) were excluded from this study. The male/female ratio of the 55 patients was 41/14. The median age of our subjects was 59 years (range 30-82 years). MM-MZL without lymph node (LN) was detected only in 9 patients (36.2%). Bone marrow (BM) involvement was observed in 17 patients (30.9%). The most common site of involvement was the gastrointestinal (GI) tract (25 patients, 45.5%) followed by the lung (40%), Waldeyer's ring (WR) (27.3%), and ocular area (25.5%). Ocular MZLs were commonly accompanied with WR- or lung-MZLs. GI-MZLs were WR or GI-MZLs. Lung-MZLs were frequently observed with ocular and GI-MZLs. WR-MZLs were ocular or GI-MZLs. A total of 53 patients were treated, and 2 on watchful wait. As much as 48 patients received chemotherapy-based treatment. Among them, CR or PR was achieved in 38 patients (79.2%, 95% CI 67-91%). Median time to progression (TTP) was 2.3 years (95% CI 1.4-3.2 years). Cause-specific overall survival (OS) did not reach the median value. The 5-year OS rate was 84.9%. MM-MZLs tend to be an indolent disease, characterized by prolonged survival with frequent relapses. The majority of cases could be controlled effectively via chemotherapy-based treatment, and prolonged survival was achieved in those patients. The GI, lung, WR, and ocular area were commonly presented with other MALT site MZLs, and an organ-specific relationship appears to be relevant to MM-MZLs.