This guidance provides recommendations to industry and FDA staff on the content and format of Dear Health Care Provider (DHCP) letters.2 DHCP letters are correspondence ― often in the form of a mass mailing from the manufacturer or distributor of a human drug or biologic or from FDA ― intended to alert physicians and other health care providers about important new or updated information regarding a human drug or biologic (hereafter “drug” and “product” refer to both biologic and small molecule drug products). DHCP letters may also be distributed by email and are often made available on the Internet (e.g., on company Web sites or through patient advocacy groups). This guidance provides recommendations on (1) when to issue a DHCP letter, (2) the types of information to include in a DHCP letter, (3) how to organize that information so that it is communicated effectively to health care providers, and (4) formatting techniques to make the information more accessible.