A system of reporting discrepancies between antemortem and postmortem diagnoses was devised for use in interdepartmental quality assurance at a large community medical center. Between 1988 and 1991, 213 autopsies comprising 6% of deaths were coded using the system of Battle et al. (1) and distributed to the quality assurance committees of clinical departments. A major discrepancy was found in 11.7% (95% confidence interval; 6.8 to 18.4%) of adult cases. The discrepancy rate tended to increase with increasing patient age, but there was no significant effect due to patient sex, race, hospital of origin, clinical department of origin, whether the autopsy was restricted to examination of only part of the body, or whether the patient died in or out of the hospital. The possible uses of the quality assurance system and problems encountered with its implementation are discussed.