“Hospitals are more like battlefields than Toyota production lines”. I wrote that years ago in response to a Lean consultant who had challenged the need for discrete event simulation in health care. Simply put, I said, health care systems are more complex, variable, and interdependent than anything encountered in modern manufacturing systems. Thus, why should we merely copy the same manufacturing improvement methodologies to this very different environment? More to the point, why not deploy different analytical tools and methods more appropriate to the far more complex world of health care? While we have certainly made some strides in improving health care processes using traditional manufacturing approaches, we clearly have a very long way to go. For instance, a recent meta-analysis of manufacturing-based improvement efforts of some 47 Emergency Departments shows only trivial performance improvements after two years of effort and expense, with some showing no improvement at all. Thus, as I have stated for years, traditional manufacturing approaches need additional tools and different approaches in health care if it is to successfully evolve.