BRDC is the most expensive disease of fattening cattle throughout the world. The reasons for this are high morbidity and mortality, weight loss, reduced food utilization, reduced quality of carcasses and extensive measures of prophylaxis and therapy. BRDC is caused by a substantial number of pathogens (viruses and bacteria), with predisposing risk factors from the ambient and host. Calves are at the highest risk of developing BRDC shortly after shipping. Lighter-weight calves appear to be at greater risk, although this has not been consistent. The complexity of BRDC makes it difficult to define the role of individual factors that predispose to or cause the disease. Stress factors may be 'necessary, but not sufficient', but they require additional effects to cause the disease. Increasing the production of meat and milk worldwide would be sustainable by improving the prevention and control of BRDC.