This publication discusses bovine leukemia virus and its prevalence, economic implications, transmission, clinical signs, diagnosis, treatment, prevention, and control. Written by Kaitlyn K. Renegar, Ameer A. Megahed, Ahmadreza Mirzaei, and João H. Jabur Bittar, and published by the Veterinary Medicine—Large Animal Clinical Sciences Department, UF/IFAS Extension, May 2023.