The term "transborder data flows" (TBDF) refers to a complex set of issues that have come to the forefront as a result of the electronic transfer or exchange of information across national boundaries. TBDF involves the flow of digital information across borders for the storage or processing in foreign computers. It reflects the interests of governments in regulating or otherwise intervening in the free flow of such exchanges for a variety of reasons, including economic, social, political, and cultural ones. An overview of these TBDF issues is provided, together with a discussion of the policies and experiences of the US National Library of Medicine pertaining to the transfer of biomedical information worldwide. Trends in the international interchange of scientific and technical information (STI) include: 1. The sharing of STI will increase among nations in proportion to new advances in science and technology. 2. As information increases in value, it will become even more susceptible to TBDF barriers. Finally, the future of US information policy is addressed.