Simulation is used extensively in industries that involve routine, but risky activities. The authors describe an anesthesia simulation environment that provides a re-creation of the anesthesiologist's task environment in a real operating room. The system provides appropriate inputs to standard monitoring equipment in common use during anesthesia, including ECG (with arrhythmias); invasive systemic arterial, pulmonary arterial, and central venous pressures (all coupled to ECG arrhythmias); automated cuff blood pressure; pulse oximetry; mass spectrometry; breathing circuit spirometry; and oxygen analysis. An intubation/thorax mannequin allows tracheal intubation and tube manipulation, and provides for simulation of occlusion, malposition, or disconnection of the tracheal tube, as well as regurgitation of gastric contents. The simulation is comprehensive in that it is "hands-on" and requires actual performance of most interventions using actual equipment. The simulation is conducted by a systems operator and a simulation director; the latter also acts in the roles of surgeon and circulating nurse. The simulator outputs are determined by a "script" that defines the consequences of routine anesthetic actions and pre-established critical incidents. Decisions about timing and override of the script are made by the simulation director. This control system offers maximum flexibility while maintaining clinical realism. The simulator experiences were judged as highly realistic by 21 subjects. Limitations in this version have centered on the mannequin (e.g., no patient movement, minimal or confusing physical signs) and will be addressed in future versions of the system. The authors suggest that anesthesia simulation can be accomplished at nominal expense and has major potential for training, continuing education, certification, and research.