The paper provides prevalence estimates of anxiety disorders as well as homotypic (e.g., other anxiety disorders) and heterotypic (e.g., mood, externalizing) co-morbidity in a national sample of children and adolescents referred to the psychiatric system in Denmark. Data were gathered from a database containing 83% of all youth referred from 2004 to 2007 (N=13,241). A prevalence of 5.7% of anxiety disorder was found in the sample. Homotypic co-morbidity was found in only 2.8%, whereas heterotypic co-morbidity was found in 42.9% of the cohort. A total of 73.6% had a principal anxiety disorder as opposed to 26.4% who had other principal diagnoses and a secondary anxiety disorder. The national database not only provides a valuable prevalence estimate of anxiety disorders in every-day non-research psychiatric settings, but also highlights the importance of applying standardized screening instruments as routine to increase the precision in recognizing and reporting on childhood anxiety disorders.