The main aim of the article is to evaluate the dynamics of the processes taking place in Polish farms after the integration with the EU. It was observed that in the period of the Polish economic boom (2004, 2006-2007 ), the operating farms would actively modernize their production potentials. It indicates a crucial role of microeconomic factors in creating reproductive processes. Widened reproduction was observed in 2004-2007 in FADN system farms while in successive period 2008-2009 the reproduction processes were restricted. However, there are considerable differences in the area owing to the existing scale of production. It has been found that in the farms of economic size larger than 16 ESU, the modernization processes provided for the widened reproduction in almost the whole of the examined period (2004-2009). On the other hand, decapitalisation of assets was dealt with in farms up to 8 ESU. A significant fall in the incomes of larger farms in 2008-2009, despite the introduced advanced level modernization processes and enlargement of production supplies, proves their strong susceptibility to economic situation change.