Since World War II there has been a great increase in the number of United States medical personnel working in the socalled "underdeveloped" areas of the world. This expansion in the delivery of scientific medicine is caused by a number of factors. Prominent among these are the great increase in military bases in foreign countries, where the doctors and nurses frequently treat native civilian personnel as well as U.S. troops, and to United States participation in international health programs such as the Pan-American Sanitary Bureau, International Cooperation Administration and other technical assistance programs.