Clinical indicators were developed and used to assess the quality of patient care resulting from the system of shared responsibility between emergency department (ED) and radiology department faculty physicians for interpretation of ED roentgenograms. The first indicator--all discrepancies in roentgenogram interpretation between ED and radiology department faculty--measured an overall discrepancy rate of 3.3% (776 films). Three hundred fifty-two apparent discrepancies were not related to the accuracy with which ED faculty interpreted films, resulting in a revised overall discrepancy rate of 1.8%. The second indicator--undesirable patient care outcomes as a result of delayed accurate radiological diagnosis--measured an occurrence rate of 0 after clinical reevaluation of more than 99% of patients within 24 hours of initial ED evaluation. Aspects of the development and use of clinical indicators are discussed in relationship to the broader monitoring and evaluating process necessary for the continuous improvement of patient care.