In the paper analyzed the total of 1688 farms, monitored by the Polish Farm Accounting Data Network in the years 2005-2013. Analyzed 1,688 households, of which 301 have evolved from mixed production farms (in 2005-2007) holdings specializing in (2011-2013) in field crops, permanent crops and milk production. The remaining 1387 households in the period 2005-2013 has not given up from a diversified production structure. The analysis conducted indicated that the specialization of production in the analyzed farms resulted in an improvement in the level of revenue, labour productivity and profitability of production.