The Diagnostic and Statistical Manual 4th edition (DSM-IV) has been widely accepted and used for international classification of mental disorder. The DSM has been changed to improve diagnostic reliability and validity through descriptive and categorical approaches which was undertaken atheoretically. The authors reviewed current studies about the DSM-IV classification system and the diagnostic issues of representative categories of anxiety disorder. The authors concluded that the anxiety disorder classification system in DSM-IV has limitations such as a lack of empirical consideration for overlapping features of anxiety disorders and a lack of discriminant validity. To improve diagnostic validity and revise the current DSM-IV classification system, the authors suggested 1) more longitudinal studies for collecting empirical evidence, 2) decreasing the dependence upon operational criteria, 3) deceasing diagnostic boundary blurring, 4) developing disease specific biological diagnostic techniques and 5) continued collaboration between the DSM and International Classification of Diseases (ICD) systems.