The accuracy in summarized diagnosis in the study was less than 50% due to a lack of diagnoses thereof in many cases or incongruity with the corresponding medical records. The possible reason why overall coding accuracy was below 65% is that coders didn’t encode or omit it when physicians failed to diagnose. Consequently, the disease data base of Siriraj Hospital and the nation is incomplete and inaccurate, further affecting the data required for research study and claiming medical expenses. This issue points to the urgency to make physicians realize the importance of accurate, complete in summarized diagnoses congruent with the written medical records, together with regular and effective follow-ups, medical record evaluation, and coding monitoring and control.