The paper analyzes the changes in agricultural trade patterns in Slovakia that occured during the gradual trade liberalization due to European Union enlargement in 2004. The results indicate that approximately 30% of the increase in agricultural imports from the EU15 and CEECs between 2000 and 2005 was due to the discriminatory trade liberalization between Slovakia and the EU15 and CEECs, i.e. due to the formation of a customs union. Part of the increase in agricultural trade with the EU15 and CEECs was at the expense of trade with more efficient producers from the rest of the world, i.e. there is an indication that some trade diversion could have occurred. The second wave of agricultural trade liberalization (from 2002 onward) brought about greater effects in terms of the increase in agricultural imports from the EU15 and CEECs than was the case with the first wave.