We surveyed the discordance rate of principal diagnosis made at emergency room(ER) & made at ward on discharge of the patients. Subjects were four hundred eighty cases who came to the ER of one third-line hospital from January 1, 1998 to January 31, 1998. The discordance rate was higher in patients admitted to medical department(8.2%) than surgical department(1.5%). If the patients were transferred to other department during hospital stay, discordance rate increased from 3.3% to 6.3%. In conclusion, discordance rate of principal diagnosis made at ER and made at ward was higher in patients with complicated problems. Medical record department should keep these findings in mind if it has a plan to support the management of ER record.