This study was to determine the procedure for ultrasonographic imaging of the canine external ear canal(ECC). By infusion of warm saline solution into the ear canal, a real-time B mode ultrasonographic examination of the ECC was performed in five healthy Beagle dogs and two dogs with severe otitis externa. The ultrasonography was very useful to detect the structures of the ECC and the tympanic membrane. An 11 NHz linear probe was permitted to assess an anechoic lumen of the ECC and a hyperechoic cartilage surrounding the ear canal. In two dogs with otitis externa, it could be assessed the ECC with ultrasonography without ear cleansing. A lumen of the ECC was irregular and a cerumen could be seen, but edematous inflammatory changes of the ECC could not be identified. The results suggest that ultrasonography of the ECC with an 11 NHz linear probe after infusing the saline solution into the ear canal may be an accurate, non-invasive, rapid, and widely available method for assessment of the ear canal diseases such as otitis externa, polyp, stenosis, hyperplasia, and foreign body in dogs.