The occurrence of monoclonal gammopathy of undeterminate significance (MGUS) in an autoimmune disease such as systemic lupus is not common but it is not as rare as the occurrence of a malignant disease such as Multiple myeloma. The complexity of this association lies in the challenges of monitoring MGUS’s patients who are likely to progress towards malignant hemopathy. Some risk factors for this progression have been described (rate of monoclonal compound, paraprotein isotype, medullary plasmacytosis or even light chains). However, none of these factors taken independently allows us to correctly categorize patients. Scores combining several of these factors have been proposed to define groups of patients with different evolving risks. The aim of this work is to report this association (systemic lupus and MGUS) in a 52 year old woman, in order to alert the clinicians about this eventuality when monitoring their lupus patients.