There are currently hundreds of published retrospective reports that fall under the rubric of'clinical trials' of AI, but they are not really trials at all. While essential for laying the groundwork, these are in silico assessments of datasets to determine how well a deep neural network performs a clinical task, compared with a small number of physicians. Such AI reports do not simulate clinical practice but instead work from a cleaned, relatively pristine, annotated dataset. The real world of medicine, in contrast, is messy, with plenty of missing data, lots of it unstructured, and its focus is caring for patients rather than developing an analytical substrate. The stark contrast of a clinical environment versus an in silico one cannot be overemphasized, and hence clinical trials of AI are needed.