Background of the empirical analysis of self-employed business start-ups is a comprehensive database, which provides realistic start-up information. In this context the author compares seven databases concerning their adequacy for research on liberal professions. The databases are the Microcensus of the Federal Statistical Office Germany, the Purchase Tax Statistics, the German Socio-Economic Panel, the ZEW Start-Up Panels for West and East Germany from the Centre for European Economic Research, the IAB-Establishment Panel of the German Federal Labour Office, statistics of the Institute for Professions (IFB) and the German General Social Survey (ALLBUS) of the German Social Science Infrastructure Services (GESIS). The databases are compared referring to its sample size, representativeness, structure and its information content. The author sums up the acceptability of the tested databases and gives an overview of the Business Register and other courses of action.