Bovine respiratory syncytial virus (BRSV) is an economically important cause of respiratory disease in cattle worldwide. The virus is an important respiratory pathogen in naïve cattle of all ages, but as with other respiratory syncytial viruses, it primarily affects young calves. The virus has also been implicated as one of the viral agents involved in the inducing phase of bovine respiratory disease complex. Efficacy of vaccines developed to protect against BRSV related respiratory disease must be demonstrated in models that exhibit clinically relevant respiratory disease in susceptible cattle. The model used in this trial involves experimental infection with a virulent field isolate of BRSV, resulting in induction of severe clinical disease and associated pneumonic lesions.