Each of six calves inoculated endobronchially with bovine herpesvirus 1 (BHV-1) by means of a bronchoscope developed viral pneumonia. Gross and histopathological lesions were mainly localized to the right diaphragmatic lobe (middle to caudal region) of the lung and were closely associated with the site of the deposition of the inoculum. The lesions were characterized by intranuclear inclusion bodies associated with focal necrosis of the epithelium in the lower respiratory tract. BHV-1 antigen and BHV particles were detected in the degenerating bronchial, bronchiolar and alveolar epithelial cells. After infection, the total cell count in the broncho-alveolar lavage (BAL) fluid increased. In addition, BHV-1 antigen and virus were detected in the desquamated cells and macrophages of BAL fluid from the right diaphragmatic lobe, but not from the left diaphragmatic lobe. It is concluded that examination of BAL fluid is valuable for immunohistopathological and virological confirmation of BHV-1 infection.