This prospective observational study was undertaken to assess the impact of a major music festival on the workload of a local hospital. Data were collected on all attendances at Naas General Hospital from the nearby Oxegen 2004 music festival. Patient demographics, disposition and diagnoses were recorded. Emergency department activity levels were compared before, during and after the festival. Seventy-two attendees were referred to Naas emergency department over a 3-day period, representing a 45% increase in the hospital's emergency department attendance rate. Thirty-seven of these attendees (51%) required inpatient or tertiary centre services. Thirty-four attendees (47%) were noted as having consumed alcohol and/or used illicit substances. We conclude that despite the provision of on-site medical facilities, major music events are associated with a significant increase in local health care activity and expenditure.