Brain drain is a term used to describe the emigration or migration of individuals who have received advanced training at home. It refers to the movement of highly skilled professionals, usually from one nation to another, in search of a better quality of life, a higher standard of living, better technologies, and more stable political conditions. Brain drain can occur at the individual, organizational, industrial, or national level.

The term "brain drain" was first used by the Royal Society to describe the emigration of "scientists and technologists" to North America from post-war Europe. Although the term originally referred to technology workers leaving a nation, the meaning has broadened into "the departure of educated or professional people from one country, economic sector, or field for another, usually for better pay or living conditions".

Brain drain can have negative impacts on the country of origin, including the loss of valuable human capital, tax revenue, and health and education service personnel. It can also lead to slower economic growth and difficulty in filling specific skill shortages. However, the receiving country may benefit from the net benefits of human capital flight, sometimes referred to as a "brain gain".

To reduce brain drain, governments can take steps to boost investment in the local economy and improve working conditions. However, given the social, political, and economic conditions in developing countries, it may be difficult to stop brain drain entirely.