Understanding cardiovascular physiology, pharmacology, and treatment of shock is heavily emphasized in current medical school and surgical training. Performance of individuals in treatment of critical illness remains poor despite regular didactic sessions. We have developed a PC computer-based simulator capable of integrating basic hemodynamic parameters to dynamically generate a realistic patient monitor. The methodology includes physiological feedback as found in humans. The trainees are able to learn through a series of scenarios or ad lib manipulation of parameters. Participants including medical students, nurses, and residents were given a pretest before attending either a 30-minute didactic or a 10- or 30-minute simulator session. A posttest was administered to evaluate performance after the intervention. Twenty-four participants were equally randomized with 12 receiving simulator training. Although the two groups had similar pretest scores (P>0.5), the simulator group showed a 24 per cent improvement, whereas the lecture group showed a 10 per cent improvement in the posttest score (P=0.008). Simulations in surgery and critical care are in early stages of development. Access to such simulators on a personal computer can greatly enhance understanding of the cardiovascular system. These simulators appear to be very effective and may become an integral adjunct to traditional classroom teaching methods.