Résumé : We here report the case of a 45-year-old patient who presented 2 invasive infections with Streptococcus Pneumoniae in 9 months period (two bacteriemias, associated with pneumonia then meningitis), in which the workup of a possible immunodeficiency led to the diagnosis of multiple myeloma, an usual pathology at this age. Although S. Pneumoniae infections are a frequent complication of multiple myeloma, they do not usually lead to its diagnosis. The mechanisms of this greater susceptibility to encapsulated germs as S. pneumoniae in multiple myeloma are discussed. In clinical practice, this case reminds us that the occurrence of at least two severe bacterial infections is a criterion to perform a search for immunodeficiency.