Mucosa-associated lymphoid tissue (MALT) is the most common extranodal lymphoma, with one third of the cases occurring in the stomach. Surgical treatment is a possible option. This case report describes an obese woman (body mass index 46 kg/m2) seeking bariatric surgery, with elevated serum cholesterol and uric acid, negative for Helicobacter pylori but with a positive biopsy for MALT (immunohistochemistry), stage IA. She was submitted to a Roux-en-Y gastric bypass and gastric resection. Two months later, she had lost 20 kg and the MALT lymphoma was in complete remission.