The following states are states to which European patent applications (direct or Euro-PCT) and thus patents can be extended (date of effect of the respective agreement with the EPO in brackets):

The EPO's extension agreements with the Republic of Slovenia (entry into force: 1 March 1994), the Republic of Romania (15 October 1996) the Republic of Lithuania (5 July  1994) and the Republic of Latvia (1 May 1995) terminated when these four countries acceded to the EPC with effect from 1 December 2002, 1 March 2003, 1 December 2004 and 1 July 2005 respectively. However, the extension system continues to apply to all European and international applications filed prior to those dates, and to all European patents granted in respect of such applications.