Multiple myeloma (MM) is a hematologic malignancy most frequently preceded by a transient state called "pre-myeloma", whose main representatives are the Monoclonal Gammopathy of Undetermined Significance (MGUS) and asymptomatic MM. The biologist has an important role in the diagnosis of monoclonal gammopathy, from initial diagnosis to monitoring. Many national and international recommendations have been published in recent years, particularly that of the National Health Authority (HAS) and of the International Myeloma Working Group (IMWG). The HAS published a guide detailing all of the management of patients with MM. These recommendations are currently restricted to France. The IMWG made recommendations for early screening of these diseases, aiming to diagnose almost all of the monoclonal gammopathies. This is not without problems, with a significant cost to the patient, particularly for the expensive serum-free light chain measurement, not recommended by the HAS. In France, there are no national guidelines for the detection of pre-myeloma pathologies. In the absence of specific recommendations for these cases, the dialogue between clinician and biologist is even more crucial for the optimal management of patients with monoclonal gammopathy, particularly for establishing a difficult diagnosis.