Patients diagnosed with multiple myeloma are more susceptible to infections which are the major causes of morbidity and mortality associated to this disease. The main infectious agents involved are Gram-positive bacteria. However, after chemotherapy an increase in the incidence of Gram-negative strains is observed. These bacteria are also responsible for most cases of urinary tract infections. Here is reported a rare case in a 73-year-old man with multiple myeloma who developed endocarditis due to pseudomonas.