A brief survey of two internal medicine practices explored clinician perceptions of individual- and systems-level factors contributing to diagnostic errors. The most commonly reported individual-level factors contributing to diagnostic error was atypical patient presentations (83%), failure to consider other diagnoses (63%) and inadequate follow-up of test results (53%). Common systems-level contributors identified were cognitive burden associated with the electronic health record system (68%), inadequate time (64%) and lack of collaboration (40%).