All patients who underwent video-assisted thoracic surgery (VATS) for diagnostic purposes from Jan. 1992 to Aug. 1995 were reviewed. The total number of patients were 111 with 57 male and 54 female, and the mean age was 49 years (range 1 to 74). Multiple biopsies from more than one location were performed in 17 patients , pleural biopsies were performed In 49 patients, lung biopsies in 43 patients, mediastinal mass or Iymph node biopsies in 33 patients, and two pericardium biopsies and one dia- phragm biopsy, for a total of 128 biopsies. Seventeen pleural biopsy cases and one lung biopsy case underwent operation under local anesthesia , the rest were performed under general anesthesia. In patients who underwent lung biopsy, the mean age was 49.1 ye rs (range 22~ 73). The operating time was 40 to 170 minutes (mean 97), intravenous or intramuscular injection for pain control was required 0 to 22 times(mean 4.7), and chest tube was inserted from 1 to 26 days(mean 7). In all patients except two, a diagnosis was obtained from the biopsy and complication was encountered in one patient in whom intraoperative paroxysmal atrial tachycardia was detected. In 7 patients, a thorn- cotomy had to be done due to pleural adhesion or intraoperative bleeding, and 7 patients had postoperative complications associated with the chest tube. In the pleural biopsy group, the mean age was 49 years (range 17~ 74). The operating time was 25 to 80 minutes (mean 49), intravenous or intramuscular injection for pain control was needed 0 to 20 times (mean 3.6), and the chest tube was i.nserted for 0 to 67 days(mean 9.8). In all the patients, a diagnosis was possible. The chest tube was inserted for longer than 7 days in 11 patients. In the Iymph node biopsy roup, the mean age was 44.2 years (range 1 ~ 68). The operating time was )0 to 3)5 minutes(mean 105), pain control was required 0 to 15 times(mean 3.2), and a chest tube was kept in place for 1 to 36 days(mean 6.1). In one patient, a diagnosis was not possible and a chest tube was kept in place for longer than 7 days in 7 patients. In the multiple biopsy group, the mean age was 53.1 years(range 20~ 71). The operating time was 15 to 165 minutes(mean 85), and pain control was done from 0 to 17 times(mean 3.1). The chest tube was kept in place for 1 to 16 days (mean 7.9).