The 4 key success factors for reimbursement by diagnosis related group (DRG) system are completed medical record, corrected medical coding, accuracy of cost data, and appropriate DRG grouping. In the past, there were many errors in coding. After the Center of Health Equity Monitoring (CHEM), Naresuan University reviewed the medical record audit of MOPH hospitals on high cost-claimed data, which were sent to the Office of Health Insurance throughout the year 2000 . The report revealed errors in coding that effect the sum of DRG relative weight: 77.86%, 54.39% and 40.85% in community, general and regional hospitals respectively.   In this circumstance, there should be a study to review their real situation in all aspects and find out the problems, their causes and the recommendation to improve the coding system in Thailand.  	To achieve the objective, several tools were utilized to reach the objectives: 322 hospital survey for real situation in coding practice, focus group discussion by 34 coders, in depth interviews of 4 executives who are interested in coding system, workshop for brainstorming by experts in coding, review corresponding literature, analysis of coding errors from hospital data, and report of 3M Health Information Systems Evaluation of the Infrastructure of Casemix  company’s study. Current situation of diagnosis and procedure coding system in Thailand	75% of hospitals in Thailand use ICD10 for coding diagnosis of diseases and ICD-9-CM for procedure. In the view of hospital executives and experts, diagnosis/procedure coding was most utilized for statistical report (75%) and for reimbursement (64.19%) .59.87% of the studied hospitals had certificated medical coders in coding practices, but 46.20% of    coder in studied hospitals had to work in other jobs. 85% of coders had been trained in diagnosis/procedure coding training course. The work experience of the coders was 43.61% in 1-3 years interval and 13.66% in <1 year.The most common method of coding was using only ICD books (53.90%). The second was ICD books with computer-aided coding program(27.80%).  And using only computer-aided coding program was the least chosen method (18.31%). The study revealed that errors on coding happened in ICD book  was 5.16%, ICD book with computer-aided coding program was 7.04% and computer-aided only  was 10.47%.   Analysis of high cost claimed data from several levels of hospital in year 1998-2000 projected a trend in data quality.  Errors in coding were declined from 38.3% in 1998 to 15.6% and 8.0% in the following years.  The most common errors were deficiency of 4th and 5th code when necessary. Problems and recommendationsProblemsRecommendations in practical viewsRecommendations in policy viewsPhysician’s discharge summary (completeness, accuracy and timeliness)  fromMisunderstanding of how to write document in medical record form.Lots of workload in patient care No recognition of the value of this work and poor incentives for workingEducate the physicians inHow to write qualified medical record.Principles to write  diagnoses and procedures in summary sheetPrinciples of diagnosis/ procedure codingMedical record audit Diagnosis related groupsAlternative way in the case of empty discharge summary e.g. filling up by nurses follow by physician’s Authentication  Hospital policy and guidelines for medical record, systematic medical record audit and utilization of information from medical record documentation.Monitoring and evaluation1.  Addition of knowledge about medical record in under graduated medical curriculum included documentation, discharge summary, coding principles, medical record audit and DRGs.      2.  Steering the process of medical record audit coordinated with hospital accreditation process and feed back to every levels of executives. Coder errors from Insufficiency Of medical coders, some hospital used other personnel who had never been trained to do the coding.Lack of knowledge, experience and carefulness in rechecking codes   Lack of Motivation in their works due to inappropriated career ladder , lack of supportive measures in professional knowledge and skills Define  specification of medical coderFor short term, training  nurses to do the coding is needed Build up consulting system in coding  e.g. medical or senior nurse  consultant Coders must be supported in continuous coding education (training course, conference)Develop expert coding software program to facilitate coder works. Increase production of medical coders that may be in 2 stages.1.1  Stage  1  Short  term planning         1.1.1  There are two training courses . First is                  in  Medical coding, Medical Record                  Auditing, Code Auditng and DRG                  Grouping for the coder.  The second                  appears to be a refreshing course for                  Medical Record Librarian.1.1.2  Conference or seminars in medical           coding       1.2  Stage 2 Long term planning              1.2.1     Increase production of medical coders   to reach the optimum and upgrading to bachelor degree1.2.2   Increase quality of instructors  by             provision of additional official training.Establish coders to be professionalsDevelop appropriated knowledge that correspond to morbidity and procedure coding system in Thailand.  Set up coding standards  Qualified licensing the coders  Guidelines for physicians to complete medical record Guidelines for medical coding practice Guidelines for medical record audit Develop performance indicators in codingInstitute “National Coding and Classification           Center”   to have the following functions:        5.1 Academic function in disease classification and medical  activities       5.2  Maintenance medical coding system       5.3  Academic support for coders.