In recent years, effective microorganisms (EMs) have been administered to humans and domestic animals, and their usefulness has been recognized for promoting health and enhancing immunity. For example, the preventative effects against flu are enhanced by ingestion of Lactobacillus by humans, and symptom relief of atopic dermatitis has been reported, with EMs actually used in commercial products. In addition, EM preparations are being used in livestock to prevent infections (e.g. Salmonella and Escherichia coli infection). In poultry, avian influenza and Newcastle disease are terrible and fatal infectious diseases that cause significant economic damage. Furthermore, countries designated as contaminated with these pathogens can experience major trade problems. Given the above, how to protect livestock from infections safely and at low cost without using disinfectants, antibiotics and vaccines is a major issue. In the present study, we examined whether or not Newcastle disease could be suppressed by feeding chickens BX-1 as an EM feed. A field strain of Newcastle virus was cloned from cloaca swabs of large numbers of dying chickens in a poultry farm in Indonesia by polymerase chain reaction (PCR) and hemaggregation assays. Chicken kidney cells and embryonated eggs were highly sensitive to this virus, and high titers of virus were able to be collected. The experimental viral inoculated to chickens showed a high mortality rate, with high pathogenicity in birds. Conventional chickens were also raised on a diet supplemented with BX-1 and directly infected with the Newcastle virus. The mortality was decreased in these infected birds. Even the low dose of BX-1 had an inhibitory effect on the lethality of the infection. These results suggest that BX-1 intake through an EM diet is effective in controlling Newcastle disease.