Objectives: Infections pose the greatest risk of early death in patients with Multiple Myeloma. However, few studies have analyzed the risk factors for infections in Multiple Myeloma patients. The aim of this study was to analyze the risk factors infections within a population-based MM cohort. Methods: Using Danish registries (from 2005 to 2013), we analyzed all ICD-10 codes for infections within the first 6 months of Multiple Myeloma diagnosis in 2557 patients. Results: Pneumonia and sepsis represented 46% of infections. Multivariable regression analysis showed that risk factors for pneumonia were male gender (HR 1.4; P = 0.001), ISS II (HR 1.6; P = 0.0004) and ISSIII (HR 1.8; P = 0.0004) and elevated LDH (HR 2.6; P = 0.0008). Risk factors for sepsis were high bone marrow plasma cell % (HR 1.1; P = 0.038), ISS II (HR 1.7; P = 0.007) ISS III (HR 2.0; P = 0.002) and creatinine (HR 2.1; P = 0.002). Neither immunoparesis (hypogammaglobulinemia) nor comorbidity was significant risk factors. Conclusions: Our study suggests that tumor burden and renal impairment are risk factors for pneumonia and sepsis in the early phase of Multiple Myeloma.