In the past two to three decades, advancing knowledge in the areas of physiology, pharmacology and scientific technology have allowed diversification from the purely technical aspects of administration of anaesthesia towards more accurate assessment of outcome for the individual in terms of both anaesthetic-induced morbidity and mortality. In addition, elucidation of the aetiology of the morbidity and mortality produced by anaesthesia, as opposed to that from surgery or concomitant medical or surgical disease processes, is assuming increased importance as a result of the expansion in medical litigation, where anaesthetists find themselves amongst the higher risk specialties in medicine. The morbidity produced by anaesthesia is relatively easy to define for specific populations, but the prediction of risk in an isolated individual remains elusive. For example, there are many studies indicating the incidence of postoperative myocardial infarction following surgical procedures in defined groups; but for the individual patient, more sophisticated risk assessments have so far failed to predict more accurately than the well-established ASA grading system. Nonetheless, it is expected that in future, studies in this area will permit increased precision in the assessment of risk, thereby permitting better consideration by both surgeon and patient of the options available regarding surgical and non-surgical therapy. Increasing emphasis on the safer administration of anaesthesia has been greatly aided by the use of the critical incident technique. By assessing near-misses in addition to existing morbidity and mortality, the technique increases the size and extent of the database, and by removal of the reticence inherent in an anaesthetist's confession of his mistakes, it increases the reporting of potential mishaps. Amongst the useful findings to have emerged from such studies is the previously unforeseen and unsuspected observation that the most dangerous period of anaesthesia is not during induction and recovery, but during the maintenance period. However, perhaps one of the more valuable aspects of this type of methodology is its potential use in quality control and audit within departments. There are undoubted problems and universally acknowledged difficulties in epidemiological research into anaesthetic mortality. Comparison of data between studies is rendered difficult owing to variations in procedure, including its prospective or retrospective nature, the definition of death, the perioperative time period studied, and the patient and hospital populations encompassed.(ABSTRACT TRUNCATED AT 400 WORDS)