The purpose of our study is to highlight the demographic characteristics, pathological features, and clinical course of multiple myeloma (MM) patients with secondary primary malignancies (SPM). A retrospective chart review was performed from January 2009 to February 2020. Patients' demographic, pathologic and cytogenetic features, treatment characteristics and clinical outcomes were collected. We identified 871 MM patients including 40 patients who developed SPM. Among the 40 patients with SPM, 17 patients developed hematological SPM and 23 patients developed solid SPM. The median time from diagnosis of MM to the occurrence of hematological SPM was 6.85 versus 3.91 years in solid SPM, with a median overall survival (OS) after diagnosis of SPM of 120 and 880 days, respectively. Interestingly, we observed that there was no significant difference in OS between MM patients with or without SPM. Multivariable analysis showed that age and autologous stem cell transplantation were independent factors associated with patients' clinical outcomes. Our study highlights the importance of understanding the etiology, biology, clinical outcome and management in MM patients with SPM.