The topic of insurance coverage and justification letters for cancer predisposition testing has been the subject of much discussion on the National Society of Genetic Counselors Cancer Special Interest Group (NSGC Cancer-SIG) listserv. Some counselors have stated that they have had difficulty in obtaining insurance coverage for their patients, while others have indicated that they would appreciate seeing examples of successful letters. The purpose of this paper is to provide practical guidance in writing successful letters of justification and to share insurance success stories in the area of cancer genetic testing.