Diversity in nomenclature and on-going dilemmas over the conceptual bases for the classification of voice disorders make it virtually impossible for the collation and accurate comparison of evidence-based data across different clinical settings. This has significant implications for treatment outcome studies. The first aim of this study was to develop a modified diagnostic classification system for voice disorders with clearly defined operational guidelines by which we might reliably distinguish voice disorders from one another. The second aim was to establish the face validity and reliability of the system as an effective diagnostic tool for the allocation of patients to different diagnostic groups for clinical and research purposes. After the Diagnostic Classification System for Voice Disorders (DCSVD) had been developed, it was used in an inter-rater reliability study for the independent assessment of 53 new consecutive patients referred to the Voice Analysis Clinics of three tertiary hospitals. There were three raters present for the assessment and diagnostic allocation of each patient. The high levels of inter-rater reliability suggest this may be a robust classification system that has good face validity and even at this early stage, strong construct validity.