BACKGROUND: The timing of tracheal extubation in patients undergoing major intraoperative procedures is controversial. Immediate postoperative tracheal extubation after liver transplantation was not popularized. But in these days, early tracheal extubation has been safely performed in certain cases and routine use of mechanical ventilation is being questioned. We performed preliminary study of our 25 liver transplantation cases to evaluate factors affecting duration and indications of postoperative mechanical ventilation. METHODS: Our 25 cases were divided into two groups by periodic difference - early 13 cases (group 1) and late 12 cases (group 2). We evaluated preoperative UNOS (united network for organ sharing) scale, intraoperative transfusion and vasopressor requirement, postoperative multiple organ complications which would have influence upon tracheal extubation. RESULTS: We found great difference between two groups in duration of mechanical ventilation (Group 1: 94.4+/-7.12 hrs, Group 2: 36.1+/-28.3 hrs) and ICU stay (Group 1: 22.8+/-8.3 days, Group 2: 11.8+/-5.5 days). CONCLUSIONS: We concluded that early tracheal extubation in selected liver transplantation cases was safe and effective because it could shorten duration of ICU stay and reduce postoperative mortality. But more experience and knowledge may be needed to get more ideal guidelines for postoperative mechanical ventilation.