The research was based on the data contained in the Farm Accounting Data Network and covers the period of the first six years following the extension of the European Union in 2004. The research units were averaged farms representing 80 regions belonging to fifteen countries of the EU-15 and the ten new member states. The total number of units representing these regions was 333, of which 226 and 107 were livestock farms and mixed farms, respectively. The aim of this paper was to indicate (i) whether the concentration of mixed farms is faster than the specialist livestock farms and whether it is more intensive in the regions of the new UE states than in the old ones, and (ii) whether farms from the new regions improve productivity faster than the farms of the old regions irrespective of their production profile. The analysis was based on the regression and data envelopment method with estimation of the Malmquist total factor productivity (TFP) index and its components. As to the first question, the main findings indicate, on average, a decrease of the total labor input, but only in the new regions, an increase in the utilized agricultural area of farms both in the old and new regions, although larger in the new member countries, and the increase of stocking density in livestock farms of the old regions and only in mixed farms of the new regions. The answer to the second question is less optimistic, because in the analyzed period, especially after 2007, pure technical efficiency decreased in both types of farms both in the old and new regions. In turn, the indexes of scale and technical efficiency change indicated some improvements. However, they concern technical efficiency of both types of farms from the old regions and only scale efficiency of mixed farms from the new regions. Varied changes in individual TFP components resulted in differences of the Malmquist indexes. Their values indicate a decrease by 3% for farms from the new regions and by 1% for mixed farms from the old regions. This confirms the conclusion that farms from the old regions better endure a generally difficult period of stagnation. We observed that, the financial standing of all farms, except for livestock farms from the old regions, deteriorated, but those from the new regions suffered greater losses.