We have used the Leiden anaesthesia simulator, which makes use of a standard anaesthesia machine and monitors, and realistically simulates the anaesthesia work place. After obtaining informed consent, 28 anaesthetists and anaesthesia trainees in one hospital took part in the study. All participants were exposed to a pre-scripted simulated "control" scenario of anaphylactic shock (phase 1). The sessions were videotaped and the performances of individual participants were evaluated using a standardized scoring scheme. During phase 2, the participants were allocated randomly to undergo training in the management of either anaphylactic shock (group A, n = 13) or malignant hyperthermia (group B, n = 15) on the simulator. After 4 months, each participant underwent a blinded evaluation session with a pre-scripted "test" scenario of malignant hyperthermia (phase 3). These sessions were also videotaped and evaluated as for phase 1. The participants in group B responded more quickly, treated better and deviated less from the accepted procedure during phase 3 than those in group A. The total performance of participants in group B during phase 3 was significantly better than those in group A. We conclude that training on an anaesthesia simulator does improve the performance of anaesthetists in dealing with emergencies during anaesthesia.