Mucosa-associated lymphoid tissue (MALT) lymphomas are known to occur in Sjögren syndrome (SS) patients, but reported cases in labial salivary glands (LSG) are rare. We report a case of 60-year-old female patient with SS who developed MALT lymphoma in the labial salivary glands during a 2-year time interval when she was participating in the Sjögren's International Clinical Collaborative Alliance, an ongoing longitudinal multisite observational study funded by the National Institutes of Health of the United States. At follow-up exam, LSG biopsy showed atypical diffuse infiltration by mononuclear cells of variable size and atypical nuclei affecting the whole specimen with destruction of glandular architecture, leading to a diagnosis of B-cell MALT lymphoma. Computerized tomography and bone marrow biopsy failed to show additional evidence of disease. Clinical, serologic, ocular, histologic and immunohistochemical findings are presented. A “watch and wait” policy was adopted with regular examinations.