To determine the rate of inappropriate use of the ambulance service a prospective study of patients brought to a Dublin accident and emergency (A&E) department by ambulance was performed over a 78-day period--358 cases were analysed representing 37% of the ambulance case load. The receiving A&E physician deemed 43.3% of cases to have a definite indication for calling an ambulance, 36.9% a relative indication and 19.8% to have no indication. A strong correlation was shown between a definite indication for transport by ambulance and admission to hospital. Acute medical illness was the most common presentation in the study group (45.8%). Patients themselves were predominant in calling for a 999 ambulance and 35.8% were deemed to have no indication for doing so. When a general practitioner requests the ambulance only 7.4% of cases had no indication for the action. Approximately one-third (31%) of 999 calls were made because the patient had no transport alternative. The problem of ambulance misuse is multifactorial and a variety of strategies are required to address the issue.