This study was done for identification of bacterial agents in calf pneumonia and determination of their antimicrobial susceptibility. Bronchoalveolar lavage was done on fourteen pneumonic and seven normal Holstein calves between 1-3 month old. In bacteriological examination on the fluid of bronchoalveolar lavage, Mycoplasma spp. were isolated from 4 (28.6%) pneumonic calves and 1 (14.3%) healthy calf. Furthermore, Arcanobacterium pyogenes was isolated from 3 (21.5%) pneumonic calves and 1 (14.3%) healthy calf. However, Fusobacterium necrophorum,Actionobacillus (Pasturella) urea, Neisseria mucosa, Staphylococcus aureus, Cardiobacterium hominis were isolated from one pneumonic calf. This is the first report of Cardiobacterium hominis from the lung of a pneumonic calf. All of the isolated bacteria had the highest susceptibility to florfenicol.