The procedure of fasting from midnight until induction of anaesthesia arose from concern that patients could regurgitate during induction of general anaesthesia when the pharyngeal and laryngeal refluxes are depressed. In this situation, the contents of the stomach do not come out of the patient's mouth, but go up into the oesophagus and trachea and are drawn back down into the lungs. This can damage the lungs, causing chemical inflammation, a condition referred to as aspiration pneumonitis or Mendelson's syndrome, a serious although rare complication of general anaesthesia. For many years, preoperative fasting has been a traditional practice for reducing this risk, but patients are being fasted for considerably longer than the evidence indicates is necessary. This article considers the current evidence for preoperative fasting times and examines why patients are still being subjected to prolonged preoperative fasting. Based on the evidence presented, recommendations are made regarding this aspect of care.