Objectives: To measure the increase in volume and age-specific rates of presentations to public hospital emergency departments (EDs), as well as any changes in ED length of stay (LOS); and to describe trends in ED utilisation. Design, patients and setting: Population-based retrospective analysis of Department of Health public hospital ED data for metropolitan Melbourne for 1999?00 to 2008?09. Main outcome measures: Presentation numbers; presentation rates per 1000 person-years; ED LOS. Results: ED presentations increased from 550 662 in 1999?00 to 853 940 in 2008?09. This corresponded to a 32 rise in rate of presentation (95 CI, 29 ?35 ), an average annual increase of 3.6 (95 CI, 3.4 ?3.8 ) after adjustment for population changes. Almost 40 of all patients remained in the ED for 4 hours in 2008?09, with LOS increasing over time for patients who were more acutely unwell. The likelihood of presentation rose with increasing age, with people aged 85 years being 3.9 times as likely to present as those aged 35?59 years (95 CI, 3.8?4.0). The volume of older people presenting more than doubled over the decade. They were more likely to arrive by emergency ambulance and were more acutely unwell than 35?59 year olds, with 75 having an LOS 4 hours and 61 requiring admission in 2008?09. Conclusion: The rise in presentation numbers and presentation rates per 1000 person-years over 10 years was beyond that expected from demographic changes. Current models of emergency and primary care are failing to meet community needs at times of acute illness. Given these trends, the proposed 4-hour targets in 2012 may be unachievable unless there is significant redesign of the whole system.