Honey bees are considered a superorganism consisting of thousands of individuals and include queen, worker and drone bees. Many bacterial diseases, especially brood rot, are seen in honey bees. Since honey bees contribute to the easy spread of infections due to their proximity within the hive and their foraging habits, the diagnosis and control of these diseases has a very critical function for the sustainability of the beekeeping sector. In this respect, it has led scientists to develop new and reliable diagnostic methods for the accurate and rapid diagnosis of bee diseases. Therefore, the importance of biochemical parameters, molecular tests and microbiological tests is increasing day by day to quickly and accurately diagnose bacterial diseases. In this section, information will be given about important bacterial diseases of honey bees and their diagnostic methods.