Objectives: To examine the significance of multimorbidity in breast cancer survivors, to explore multimorbidity in treatment decisions, and survivorship, and to consider multimorbidity assessment in clinical practice. Data Sources: Literature review; clinical practice guidelines. Conclusion: Multimorbidity influences treatment decisions. Breast cancer survivors report greater multimorbidity compared with other cancer survivors. Multimorbidity increases with age; there may be racial and ethnic differences. Multimorbidity is associated with symptom burden, functional decline, low adherence to surveillance, and early retirement. Implications for Nursing Practice: Clinical practice guidelines do not refer to multimorbidity and patient outcomes. Comprehensive geriatric assessment combined with survivorship care plan may be considered.