Among the many catalogs of museum collections, few describe objects related to the practice of medicine. This catalog is the first of a series on the medical sciences collections in the National Museum of History and Technology (NMHT). Bloodletting objects vary from ancient sharp-edged instruments to the spring action and automatic devices of the last few centuries. These instruments were used in a variety of treatments supporting many theories of disease and therefore reflect many varied aspects of the history of medicine. Beginning with an essay sketching the long history of bloodletting, this catalog provides a survey of the various kinds of instruments, both natural and.