The Food and Drug Administration (FDA or Agency) is announcing the availability of a draft guidance for industry entitled “Rare Diseases: Natural History Studies for Drug Development.” FDA is publishing this draft guidance to help inform the design and implementation of natural history studies that can be used to support the development of safe and effective drugs and biological products for rare diseases. A natural history study collects information about the natural history of a disease in the absence of an intervention, from the disease's onset until either its resolution or the individual's death. Although knowledge of a disease's natural history can benefit drug development for many disorders and conditions, natural history information is usually not available or is incomplete for most rare diseases; therefore, natural history information is particularly needed for these diseases.