Mucosa-associated lymphoid tissue-derived lymphoma (MALT lymphoma) is usually a very indolent lymphoma, described as localized at diagnosis and remaining localized for a prolonged period; dissemination occurs only after a long course of evolution. In our database, out of 158 patients with MALT lymphoma, 54 patients presented with a disseminated disease at diagnosis. Of these 54 patients, 17 patients (30%) presented with multiple involved mucosal sites; 37 patients (70%) presented with 1 involved mucosal site, but in 23 of these patients (44%), dissemination of the disease was due to bone marrow involvement; 12 patients (22%) had multiple lymph node involvement; and 2 patients (4%) had nonmucosal site involvement. No significant difference in clinical characteristics (sex, age, performance status, B symptoms) and biological parameters (hemoglobin [Hb] and lactate dehydrogenase levels) was observed between localized or disseminated MALT-lymphoma patients. Only beta2-microglobulin level was significantly more elevated in disseminated disease patients than in localized disease patients. Complete response after the first treatment was achieved in 74% of the patients, and there was no difference between the 2 groups. With a median follow-up of 4 years, the estimated 5- and 10-year overall survival rates were similar in the 2 groups, 86% and 80%, respectively. The median freedom-from-progression survival was 5.6 years for all patients, surprisingly without any difference between localized and disseminated MALT-lymphoma patients. In conclusion, MALT lymphoma is an indolent disease but presents as a disseminated disease in one-third of the cases at diagnosis. The dissemination does not change the outcome of the patients.