The discovery of Helicobacter pylori and its relationship to upper gastrointestinal tract diseases has emphasized the significance of infectious pathogens in clinical disease. Severe manifestations of H. pylori-associated diseases include gastric adenocarcinoma and the recently described gastric mucosa-associated lymphoid tissue (MALT) lymphoma. Ongoing worldwide investigations of the interactions of H. pylori and the host response are rapidly clarifying the role of this bacterium in multiple gastrointestinal diseases. This review will address diagnosis, management, and follow-up of the patient presenting with gastric MALT lymphoma, including a discussion of the issues related to premalignant lesions associated with gastric adenocarcinoma. Prospective trials and long-term follow-up studies are in progress and will guide appropriate management of these diseases.