What type of doctors are eligible to write the letter?
The State Department requires that the doctor writing the letter be a licensed physician who has treated the applicant for "gender-related care" or reviewed and evaluated the applicant's "gender-related medical history." This includes medical doctors (M.D.) and Doctors of Osteopathy (D.O.). Any licensed doctor who meets these requirements can write the letter. There is no required specialty for the doctor. The following are just examples of common specialists involved in transgender health care: family practitioners, internists, endocrinologists, gynecologists, surgeons, psychiatrists, and pediatricians.
Certifications or statements from people other than licensed physicians (e.g., psychologists, nurse practitioners, health practitioners) are not acceptable.
Foreign doctors may write the letter, but their credentials must be verified, which could delay your application. If possible, consider getting your letter from a physician licensed in the U.S.
Next: What must my doctor's letter include?
Previous: Where can I find the official policy regarding sex designation changes on passports?