American Jim Yong Kim has been chosen to be the next president of the World Bank.
His selection extends the US's hold on the top job at the 187-nation development agency.
Mr Kim, a surprise nominee of President Barack Obama, was selected in a vote by the World Bank's 25-member executive board. He will succeed Robert Zoellick who is stepping down after a five-year term.
Developing nations waged an unsuccessful challenge to Mr Kim, 52, a physician and pioneer in treating HIV/Aids and tuberculosis in the developing world.
Mr Kim's selection marks a break from previous World Bank leaders who have typically been political, legal or economic figures.
The World Bank raises money from its member nations and borrows from investors to provide low-cost loans to states.
Developing countries had put forward two candidates for the post: Nigerian finance minister Ngozi Okonjo-Iweala and former Colombian finance minister Jose Antonio Ocampo. Both argued that it was time to break the US's hold on the World Bank job and provide a voice for other, less-developed countries.
Mr Kim will begin a five-year term in July. Born in South Korea, Mr Kim moved to the US with his family at age 5. His selection extends the practice of Americans leading the World Bank, dating to the institution's founding in 1944.
Mr Kim and the other candidates were interviewed by the World Bank's board last week. In his statement to the board, Mr Kim said he had worked throughout his career for "reform and change" and would continue those efforts at the World Bank.
His nomination won widespread praise because of his extensive experience in working to improve health in the poorest countries. In the 1990s Mr Kim defied sceptics to find a cost-effective way to fight tuberculosis in the slums of South America. He also began a programme that has treated millions of Africans for HIV, the virus that causes Aids.