In addition to the EPC contracting states, it is also possible to extend a European patent application for up to six extension states, namely:

Albania (GDP $5.6bn, pop. 3.5m), Lithuania (GDP $17.3bn, pop. 3.5m), Latvia (GDP $9.8bn, pop. 2.3m), Macedonia (GDP $7.6bn, pop. 2m), Romania (GDP $87.4bn, pop. 22.3m) and Slovenia (GDP $21.4bn, pop. 1.9m). The addition of each of these countries requires payment of an official fee.