Efficiency and competitiveness of Polish ecological farms differing in terms of economic size have been analyzed as well as their production potential, intensity and costs. The research was conducted in 2013-2016. Information was obtained from farm accountancy records of FADN included in the following publications: Technical-economic parameters according to groups of farms participating in the Polish edition of FADN in 2013-2016. The following methods have been used: descriptive, with the use of tables, and comparative. In 2013-2016, production potential, efficiency and competitiveness of ecological farms depended on their economic size. Farms with an economic size of 25-50 thousand euro and 50-100 thousand euro using, respectively: 37.7 and 70.3 ha AL, turned out to be able to cope with competition. However, farms with smaller areas and smaller economic size were not able to withstand competition. Farms able to withstand competition gained positive income from management in 2013-2016, however in farms without competitive abilities, this was negative. In farms with competitive ability, with an economic size of 25-50 thousand euro, payment for own labor was 1.5 times higher than the average wage in the domestic economy and in farms with an economic size of 50-100 thousand euro, it was nearly three times higher. Agricultural holdings without competitive abilities (below 25 thousand euro) did not achieve parity of own labor input return.