The paper focuses on the analysis of the changes in the production potential of Polish farms after implementing CAP mechanisms (2004-2011). Two criteria were used to share the farms: investment activity and economic size. Only those farms were selected, which continuously conducted the agricultural accounting FADN system in 2004--2011. Based on the analysis it was found that in the base period, farms making the most complex investments (supported by EU funds or financed on the basin of own financial resources), had greater production potential – in the matter of area and volume of assets. The investment activities contributed to the increase in disparities between groups of farms. Especially the non-investment farms were able to preserve the area of agricultural land, but the value of their assets was significantly reduced.