We estimated the validity, i.e., whether the diagnostic criteria were fulfilled for the patients registered with the diagnosis of liver cirrhosis in a Danish hospital discharge registry, and the completeness, i.e., whether all patients with liver cirrhosis were included in the registry. Information in the regional hospital discharge registry in the Country of Aarhus, Denmark was compared with hospital records and information in a pathology registry. 85.4% of the patients registered with a diagnosis of liver cirrhosis fulfilled the diagnostic criteria for the diagnosis (validity). 93.2% of the patients registered with biopsy proven liver cirrhosis in the pathology registry were found in the discharge registry (completeness) with a diagnosis of liver cirrhosis. The hospital discharge registry showed relatively few misclassifications and the Danish National Registry of Patients (NRP), which is based on the regional registries, may provide a unique study base for future research.