PIP: This paper examines the impact of internal migration and external population movements and interactions on the spread of the HIV/AIDS epidemic in Botswana. A total of 292 mobile workers in selected rural and urban areas were interviewed. Focus group discussions were conducted in all sites. The study showed that migration has a significant influence on public health and HIV/AIDS spread in the country. The frequency of sexual intercourse among migrant workers and their return visits back home, intensifies the spread of HIV/AIDS. Unprotected sex is a primary mode of HIV/AIDS and sexually transmitted disease transmission among the population. Despite the high level of knowledge about HIV/AIDS, its transmission and effects, there remained an insufficient use of condoms. Areas that are sites of major development projects, where a large number of migrant workers concentrate, have higher HIV and STD rates than areas that are not.