Brain drain, which is the action of having highly skilled and educated people leaving their country to work abroad, has become one of the developing countries concern. Brain drain is also referred to as human capital flight. More and more third world science-and-technology-educated people are heading for more prosperous countries seeking higher wages and better working conditions. This has of course serious consequences on the sending countries. While many people believe that immigration is a personal choice that must be understood and respected, others look at the phenomenon from a different perspective. What makes those educated people leave their countries should be seriously considered and a distinction between push and pull factors must be made. The push factors include low wages and lack of satisfactory working and living conditions. Social unrest, political conflicts and wars may also be determining causes. The pull factors, however, include academic freedom and extensive funds for research. Brain drain has negative impact on the sending countries economic prospects and competitiveness. It reduces the number of dynamic and creative people who can contribute to the development of their country. Likewise, with more entrepreneurs (企业家)taking their investments abroad, developing countries are missing an opportunity of wealth creation. This has also negative consequences on tax revenue and employment. Most of the measures taken so far have not had any success in softening the effects of brain drain. One option is to provide adequate working and living conditions in the sending countries. Another option should involve encouraging the expatriates (侨民)to contribute their skill to the development of their countries without necessarily moving back home. Another term used for 'brain drain' in this passage is '______'.