Efforts to identify the underlying structure of 40 survey items dealing with perceptions of medical errors are reported on the basis of responses from 195 medical residents. Factor analysis revealed that the medical errors perceptions were represented by a 10-factor solution. The external validity of these factors was examined relative to perceptions about the cost of medical errors, the cost of errors to health care, and the need for education and interventions to address errors. Results indicated that 13.9% of the variation in the perceived cost of medical errors and 17.1% of the variation in the perceived need for additional physician education was explained by the factor structure.