Four former East Bloc countries that have just joined the European Union - the Czech Republic, Hungary, Poland and Slovakia - can be explored with rail passes for sale in the United States by Rail Europe.

The passes provide unlimited travel for various periods and in some cases can be combined with the standard Eurailpass, good in 17 countries. Fares range from $40 round-trip from any point on the border of the Czech Republic to Prague, to $225 for five days in a 30-day period throughout the Czech Republic, Hungary, Poland, Slovakia and Austria. The new Hungary-Romania pass starts at $170 a person for five days of first-class travel.

Information: Rail Europe, (888) 382-7245, or www.raileurope.com.