The Lloyd E. Rozeboom mosquito collection from the Johns Hopkins University School of Hygiene and Public Health, Baltimore, MD, has been transferred to the National Museum of Natural History, Smithsonian Institution, Washington, DC. This historically and taxonomically important collection has specimens representing 32 genera, 78 subgenera, and 763 species from most mosquito faunal areas of the world. The collection consists of 12,015 individually pinned and labeled adults, and 7,179 microscope slide preparations of immature stages and male and female genitalia. A tabulation of genera, subgenera, species, countries, faunal areas, and number of specimens for each type of preparation is provided.