Intensive care units are complex and dynamic clinical environments in which the delivery of appropriate and timely care to critically ill patients depends on the integrated and efficient actions of providers with specialized training. The use of realistic clinical simulator systems can help to facilitate and standardize the training of critical-care physicians, nurses, respiratory therapists, and pharmacists without having the training process jeopardize the well-being of patients. In this article, we review the current state of the art of patient simulator systems and their applications to critical-care medicine, and we offer some examples and recommendations on how to integrate simulator systems into critical-care training.