Objectives: Multiple myeloma (MM) patients are at high risk of developing infections. The risk factors for blood stream infections (BSI) in MM patients are, however, less described. The aim of this study was to analyze the epidemiology of and risk factors for BSI in an unselected MM population. Methods: Nationwide Danish MM data of 1154 patients diagnosed from 2010 to 2013 were linked with nationwide data on blood cultures (BCs; from 2010 to 2016) to assess the peak period of having a BC taken and BC positive for pathogenic microorganisms. Results: The highest number of BC was taken in the period from day −30 to day +180 from date of MM diagnosis. Risk factors for having a BC sampling within the peak period were as follows: immunoparesis (HR 1.5 [1.1-2.1]; P =.007), ISS-III (HR 1.3 [1.0-1.7]; P =.035), high creatinine (HR 1.4 (1.0-2.0); P =.046), and high lactate dehydrogenase (LDH) (HR 2.8 (1.6-4.7; P <.001). Risk factors for positive BC during the peak period were ISS-III (HR 2.0 (1.1-3.7); P =.023) and high LDH (HR 3.4 [1.1-10.3]; P =.028). Conclusions: Our results show that MM patients with aggressive disease presentation are at the highest risk of developing BSI. Furthermore, our study implies that MM is diagnosed in relation to a serious infection for a large number of patients.