Background and aims: Comprehensive geriatric assessment (CGA) may benefit frail or chronically ill patients in the emergency department (ED), but take too much time to be performed routinely in ED. An alternative approach is to use first a screening tool to detect high-risk patients and then perform CGA in these patients only. This systematic review focuses on the use and value of CGA in ED for evaluation of older patients and its influence on adverse outcomes. This approach is compared with an alternative one using existing screening tools, validated in ED, to detect high-risk patients needing subsequent CGA. This review ends by suggesting a short assessment of CGA to be used in ED and ways to improve home discharge management from ED. Methods: A systematic English Medline literature search was conducted in December 2009, with no date limit with the following Medical Subject Heading (MeSH) terms: “Frail Elderly”, “Health Services for Aged”, “Community Health Nursing”, “Emergency Service, Hospital”, “Geriatric Assessment”, “Patient Discharge”, “Risk Assessment” and “Triage”. Results: We selected 8 studies on CGA efficiency and 14 on screening tools. CGA in ED is efficient for decreasing functional decline, ED readmission and possibly nursing home admission in high-risk patients. As CGA takes too much time to be performed routinely in ED, validated screening tools can be applied to detect high-risk patients who will benefit most from CGA. Conclusions: The selected studies demonstrated that screening of high-risk patients is more efficient than age-based screening, and that CGA performed in ED, followed by appropriate interventions, improves outcomes.