Problems of patient safety have been well documented in hospitals. However, we have very limited data about patient safety problems among home care clients. The purpose of this study was to assess the burden of safety problems among Canadian home care clients using data collected through the Resident Assessment Instrument - Home Care (RAI HC), and to explore the role of age and patient safety risk factors in explaining variations in adverse outcomes, with a particular focus on emergency room visits. The study methodology involved a secondary analysis of data collected through the Canadian Home Care Reporting System. The study sample consisted of all home care clients who qualified to receive an RAI HC assessment from Ontario, Nova Scotia and Winnipeg Regional Health Authority for the 2003-2007 reporting period. There were a total of 30,396 cases with a paired intake and 12-month follow-up assessment available for analysis. New falls, unintended weight loss, new emergency room (ER) visits and new hospital visits were the most prevalent adverse outcomes. A history of falls, a cancer diagnosis, polypharmacy, receiving an anxiolytic medication and receiving an antidepressant medication were associated with an increased risk of ER visits, while low self reliance and limitation in activities of living were associated with a decreased risk of ER visits. Understanding clients'risk profiles is foundational to effective patient care.