SummaryBlood agar medium was tested for use in culturingBacillus larvaefrom diseased honeybee larvae for the diagnosis of American foul brood disease. It gave superior results to other commonly used media. Preparations stained with Gram stain were easier to interpret in microscopical examinations for spores and vegetative cells than those stained with nigrosin. LikelyB. larvaeisolates were confirmed by negative results in the catalase test. Using this method, confirmation of American foul brood disease could be achieved in 48 h.