Background Data on self-reported cardiovascular and metabolic diseases are available for the first 100,000 participants of the population-based German National Cohort (GNC, NAKO Gesundheitsstudie). Objectives To describe assessment methods and the frequency of self-reported cardiovascular and metabolic diseases in the German National Cohort. Materials and methods Using a computer-based, standardized personal interview, 101,806 participants (20-75 years, 46% men) from 18 nationwide study centres were asked to use a predefined list to report medical conditions ever diagnosed by a physician, including cardiovascular or metabolic diseases. For the latter, we calculated sex-stratified relative frequencies and compared these with reference data. Results With regard to cardiovascular diseases, 3.5% of men and 0.8% of women reported to have ever been diagnosed with a myocardial infarction, 4.8% and 1.5% with angina pectoris, 3.5% and 2.5% with heart failure, 10.1% and 10.4% with cardiac arrhythmia, 2.7% and 1.8% with claudicatio intermittens, and 34.6% and 27.0% with arterial hypertension. The frequencies of self-reported diagnosed metabolic diseases were 8.1% and 5.8% for diabetes mellitus, 28.6% and 24.5% for hyperlipidaemia, 7.9% and 2.4% for gout, and 10.1% and 34.3% for thyroid diseases. Observed disease frequencies were lower than reference data for Germany. Conclusions In the German National Cohort, self-reported cardiovascular and metabolic diseases diagnosed by a physician are assessed from all participants, therefore representing a data source for future cardio-metabolic research in this cohort.