Globally, alcohol use is among the most important risk factors related to burden of disease, and commonly emerges among the ten most important factors. Also, alcohol use disorders are major contributors to global burden of disease. Therefore, accurate measurement of alcohol use and alcohol-related problems is important in a public health perspective. The Alcohol Use Identification Test (AUDIT) is a widely used, brief ten-item screening instrument to detect alcohol use disorder. Despite this the factor structure and comparability across different (sub)-populations has yet to be determined. Our aim was to investigate the factor structure of the AUDIT-questionnaire and the viability of specific factors, as well as assessing measurement invariance across gender, age and educational level.We employed data (N = 4,318) from the ongoing screening study in the Norwegian national WIRUS project. We used Confirmatory Factor Analysis (CFA) to establish the factor structure of the AUDIT. Next, we investigated the viability of specific factors in a bi-factor model, and assessed measurement invariance of the preferred factor structure.Our findings indicate the AUDIT is essentially unidimensional, and that comparisons can readily be done across gender, age and educational attainment.We found support for a one-factor structure of AUDIT. To the best of our knowledge, this is the first study to investigate the viability of specific factors in a bi-factor model as well as evaluating measurement invariance across gender, age and educational attainment for the AUDIT questionnaire. Therefore, further studies are needed to replicate our findings related to essential unidimensionality.