The aim of this study is to compare information on hospitalisations for acute myocardial infarction (AMI) from three different sources. METHODS: (A) The national hospital discharge statistics, covering all hospitalisations in Germany, is representative for this population. However, the information is limited, as data are collected case-related containing only few characteristics. (B) In contrast, claims data of sickness funds can be analysed longitudinally and contain more characteristics. The data have to be collected from single sickness funds. As for the data from registries (C) these data cannot be assumed to be representative. RESULTS: Data from the included sickness fund showed good consistency when compared to data from the national hospital discharge statistics regarding most, but not all, results. Comparisons with the register in Augsburg lead to divergent results regarding case fatality rates and rates of utilisation of technologies. CONCLUSIONS: None of the three sources can be considered ideal. Part of the differences could be explained by methodological and regional effects. More insight could be gained by comparing data at the individual level. According to recent legislation, data from all statutory sickness funds are supposed to be merged. This would simplify such comparisons and most likely would allow for more valid information regarding the incidence and treatment of AMI and many other diseases.