Th e purpose of the paper is to investigate the relative technical effi ciency of the agricultural sector in the European Union (EU) using the Data Envelopment Analysis (DEA) during the period 2007-2011. Th e authors investigated efficiency using both the input and output-oriented models with the assumption of a variable return to scale. Th ey looked for causes of ineffi ciency and made recommendations for ineffi cient agricultural sectors. Th e results show that, in average, the EU agricultural sectors performed effi ciently, as evidenced by the relatively high value of the average input and output efficiency. Th e effi ciency of the EU agricultural sectors had changed over the past few years, and in both models the effi ciency has generally decreased over time. As the main source of ineffi ciency was labelled the input "total utilised agricultural area" and as the strength with a positive impact on effi ciency, there was labelled the "crop output. " By calculating the optimal values for the input and output variables for ineffi cient agricultural sectors, it has been found that for the effi cient production of a given quantity of outputs, it was necessary to reduce the value of the in put "total labour" in average by 6.18%, the "total utilised agricultural area" in average by 14.45% and the "total assets" in average by 5.93%. In case of the output-oriented model for effi cient use of a given quantity of inputs, the agricultural sectors should produce up to 111.85% of their crop output and 113.41% of their animal output.