Objective: To examine and compare the research productivity of the European Union, the four "candidate" countries (those currently waiting to join the EU), and the United States in several fields of biomedical sciences.
Design: A retrospective observational study-bibliometric analysis.
Data sources: Manuscripts published by authors from each country separately and from each group of countries for the period 1994 to 2004 and included in the Essential Science Indicators database of the Institute of Scientific Information.
Main outcome measures: Number of published articles and number of citations, adjusted for gross domestic product and population size.
Results: 1,485,749 articles were published by authors from the EU compared with 1,356,805 from the US. The research productivity of the first 15 countries to join the EU, adjusted for population, was lower (76%) than that of the US-and even lower (66%) when the 10 newest EU countries were included in the analysis.
Conclusion: The newest EU members and the EU candidate countries need further help and resources to increase their productivity, thereby improving the productivity of the EU as a whole.