Lists are often cited a means of removing error from a process. The most visible manifestation of this is Gawande’s influential “Checklist Manifesto” which argues that the use of lists (in a medical context) can remove or at least greatly reduce the incidence of error. In this paper I examine the error rate associated with a simple but involved medical procedure performed by a non-specialist several times and examine associated errors and what their presence may mean for the absolute reliability of checklists.