The third world brain drain problem contains elements of economic, social and political complexities. The neo-classical economic theory may, therefore, be deficient in explaining brain drain. A number of studies have focused on the effects of brain drain rather than the causes. Moreover, data availability was a problem in previous studies. This paper is concerned with a dis aggregated analysis of the determinants of immigration of engineers and scientists to the U.S. from the third world countries. Attempt has been made to explain the third world professional immigration to the U.S. with a variant of Arrow-Capron model (1959). This analysis supports the view that labor market shortages explain the immigration of engineers and scientists to the U.S. An immigrant income taxation proposal may be effective in compensating the third world countries and in stopping professional immigration .