Hepatitis B virus infection is a serious problem globally, and particularly in the Western Pacific Region where the population suffers disproportionately from the infection and its sequelae. By 2001, every immunization programme in the Region had included hepatitis B vaccine in their schedule. However, many challenges remain if every one of the 26 million children born in the 37 countries and areas of the Region each year is to be protected against hepatitis B infection. In 2003, the Regional Committee of the World Health Organization's Western Pacific Region resolved to improve hepatitis B control by making it one of two new pillars for strengthening the Expanded Programme on Immunization. The Committee endorsed the strategies of the Regional Plan to improve hepatitis B control through immunization, reducing chronic HBV infection (chronic carriage rate) to less than 1%, and aiming for coverage of at least 80% of the birth cohort in every district with three doses of hepatitis B vaccine by 2005. To help guide this process, an assessment was made of the progress to date, and is reported in this paper. Coverage data used in this evaluation were not independently verified, and could over-estimate progress made in some countries. Whilst there has indeed been great progress in the Region, a number of national programmes still lack the ability to reach all children with immunization services. Other major issues that need to be addressed are the challenges of delivering a timely birth dose, and for certain countries, the affordability of the vaccine over the short- and long-term.