Background Primary gastric lymphomas are non-Hodgkin lymphomas that originate in the stomach and are divided into low-grade and high-grade types. Low-grade lesions nearly always arise from mucosa-associated lymphoid tissue (MALT) secondary to chronic Helicobacter pylori infection and disseminate slowly. High-grade lesions may arise from a low grade-MALT component or arise de novo and can spread to lymph nodes, adjacent organs and tissues, or distant sites. Our aim was to analyse the cases of non-Hodgkin lymphomas with gastric involvement treated at a university hospital in southeastern Brazil and to assess the role of surgery in their treatment. Methods We did a survey of cases of gastric lymphoma treated at Hospital São Paulo-UNIFESP from 1996 to 2012. Findings A total of 626 cases were diagnosed with non-Hodgkin lymphoma, 30 cases with gastric involvement (5%). Among these, 19 cases were female and 11 were male, with a median age of 56.5years. Fourteen cases were diagnosed as extranodal marginal zone lymphoma of MALT: 10 were H pylori (HP)-positive, one was HP-negative, and three had unknown HP status. Fourteen cases were diagnosed as diffuse large B-cell lymphoma (DLBCL) and two cases as post-transplant lymph proliferative disorders (PTLD). 70% had localised disease (I–II). Twelve cases of MALT were treated with antibiotic therapy, followed by chemotherapy or radiotherapy (refractory cases), and two patients were treated solely with antibiotics. DLBCL cases received chemotherapy with an anthracycline-based regimen (recently associated with immunotherapy) and adjuvant radiotherapy in cases of localised disease. PTLD cases were treated with a reduction in immunosuppression and R-CHOP. Only 10 cases (33%) underwent surgery, the last in 2003. Interpretation HP was present in almost all cases of MALT, determining the therapeutic choice. DLBCL were treated systemically with chemotherapy/immunotherapy, followed by adjuvant radiotherapy in localised disease. There has been no indication for surgery in our hospital for this pathology for the past 10years, and surgery is currently restricted to complications such as perforation and haemorrhage.