The increase in size and numbers of general hospitals in the process of conspicuous development of modern medicine has been accompanied by a serious increase in hospital acquired infections. Hospital aquired infections cause pain and discomfort, may threaten life, adds an economic burden, and delays recovery and return to society. Even though respiratory hospital infection rates resulting for tracheostomy and respiratory inhalation therapy, may be low, they are serious because of their bad prognosis and high mortality rates. This study was designed to assess certain aspects of respiratory infections of patients with a tracheostomy and thus provide baseline data for further research related to preventive or therapeutic nursing interventions. The specific objectives were to determine the incidence of colonization in the trachea, clinical signs, type of colonized bacteria and sensitivity to antibiotics. Data were collected from July 1 to December 10, 1989 at two university Hospital in Seoul. Subjects were 20 patients with a tracheostomy admitted to the Intensive Care Unit or Cerebral Vascular Accident Center. Clinical signs related to respiratory infection were observed using a checklist based on previous study outcomes. Bacterial culture, sensitivity test to antibiotics, WBC counts and chest X-ray were also performed. Cultures were done on the day of tracheostomy, and on the third, fifth and seventh day. Cultures were then done on seventh days after the first colonization. The results were as follows: 1. The incidence of bacteria colonization in a week was 90%(18 patients) : 50% (10/20 patients) on the day of tracheostomy, 70 %(7 /10 patients) on the third day, and 0 % on the fifth day, and 33 %(1/3 patient) on the seventh day. 3 of 18 patients (16.7%) were colonies of mixed growth isolated. 2. The observed clinical signs related to respiratory infection were high fever 38.9 %(7 patients), prulent secretion 16.7 %(12 patients) and infiltration seen on chest X-ray 33.3 %(6 patients). 3. The total number of types of bacteria isolated among the 18 subjects was 21 I gram negative 71.4 %, gram postive 28.6 %. The dominant bacteria type was Staphylococcus aureus(5 cases) for gram and Pse-udomonas aeruginosa(3 cases), Klebsiella (4 cases), Enterobacter(3 cases) for grame. The results of culture on 7th day after the first colonization, 6 cases showed same type of bacteria, 3cases showed different type of bacteria and 1 cases showed no growth. 4. The sensitivity tests to antibiotics showed that Pseudomonas aeruginosa and Staphylococcus were strongly resistant to most kinds of antibiotics, but Klebsiella and the rest of gram negative bacteria were moderately sensitive to antibiotics.