In 1988, the World Health Assembly (WHA) resolved to eradicate poliomyelitis globally. Since then, implementation of the eradication strategies reduced the number of countries with endemic polio from 125 in 1988 to six in 2003. However, in 2003, an unprecedented 10 countries reported poliovirus importations, including eight in West and Central Africa, one in Southern Africa (Botswana), and one in the Middle East (Lebanon). This report describes progress made toward global polio eradication during January 2003-April 2004, outlines remaining challenges, and underscores the need for decisive action to interrupt transmission by the end of 2004 or early 2005.