Ninety-nine dogs diagnosed as tracheal collapse were reviewed for 2002-2003 year at Veterinary Medical Teaching Hospital, Seoul National University with clinical records and radiographs. Dogs were ranged in age from 1 to 15 years old (average 8.23 years old) and in weight from 1.2kg to 10.3kg (average 3.3kg). The population included 58 females (6 spayed) and 41 males (8 castrated). It is highly predominant in Yorkshire terrier (64, 64.6%) followed by Pomeranian (10, 10.1 %), Poodle and Chihuahua (8, 8.1%), Maltese (4, 4.0%), mixed breed (3, 3.0%), Cocker Spaniel and Pug (1, 1.0%). The incident rate of female dogs (59%) exhibited relatively higher than that of male dogs (41%). The most prevalent occurrence location was thoracic inlet (60%) of all and carina region (15%), intrathoracic trachea (14%) and cervical trachea (11 %) showed similar rate. Conclusively, tracheal collapse was observed in completely matured or old small breed dogs, largely Yorkshire terrier, on thoracic inlet primarily regardless of gender. These tendencies were apparently similar to previous reports.