Polish beer market is characterised by a high degree of concentration. The market share of Kompania Piwowarska, Grupa Żywiec and Carlsberg Polska is 90%. Many authors stress concentration as an important factor when explaining why various industries are more or less effective or more or less profitable. Firms from concentrated industries report, on average, higher profitability than those in non-concentrated industries. The aim of this paper is to analyse the differences of economic efficiency of large (group I) and small (group II) entities involved in the production of beer. Evaluation of the effectiveness of the test group of companies was based on selected financial ratios (return on assets, return on sales, inventory turnover, total debt ratio).