While implementation of computerized provider order entry systems is widely recommended, prior research has raised the concern that CPOE may lead to unintended effects on patient safety. In this study, the authors sought to classify the frequency of unintended consequences—positive and negative—encountered in hospitals that have implemented CPOE. Unintended consequences were classified based on the authors' previously developed taxonomy. Survey respondents felt that unintended consequences were widespread, primarily relating to changes in provider workflow and communication. Failure to anticipate these issues may have played a role in widely publicized instances of problems with CPOE implementation.