Recent studies have suggested that most firms do not grow, and that a small number of high-growth firms create most new jobs. High-growth firms have therefore attracted an increasing amount of attention from researchers and policymakers. However, there is no uniform definition of what constitutes a high-growth firm in the literature. Eurostat and the Organisation for Economic Co-operation and Development (OECD) recently recommended that highgrowth firms should be defined as firms with at least ten employees in the startyear and annualized employment (or sales) growth exceeding 20% during a 3- year period. This definition would exclude almost 95% of surviving firms in Sweden and about 40% of new private jobs during 2005-2008. We therefore advise caution in using this definition.