Assuming that all patients are created equal may lead many to suffer prolonged, frustrating, and expensive trial-and-error therapy, in which one treatment after another is attempted in an effort to remedy patients’ maladies. Critics of this traditional kind of care champion a new approach – personalized or precision medicine – in which genomic testing might help us understand and remedy the ravages of rare genetic illnesses as well as energize efforts to treat more common afflictions. After three decades of well-funded research, has personalized medicine measured up to the hype of its ushering in a fresh paradigm for delivering unsurpassed health care? Has it displaced trial-and-error treatment? Or is personalized medicine itself undergoing a trial-and-error process of development and testing? These and other questions must be answered if we are to best deploy limited resources to combat a wide variety of diseases – from individual genetic disorders to devastating pandemics.