BACKGROUND: We had undergone this study to investigate clinical progress of this disease and to decide the role of aggressive diagnostic approaches, the efficacy of treatments and prognoses. METHODS: A retrospective study was done on 113 patients who had been diagnosed to metastatic adenocarcinoma of pleura by pleural fluid cytology (106 cases) or pleural needle biopsy(22 cases), at Presbyterian Medical Center, from Jan. 1990 to Dec. 1994. RESULTS: 1) The patients were composed of 59 males(52.2%) and 54 females(47.8%), and the mean age distribution was 57.4 +/- 12.1 years. 2) The site of origin was lung cancer 46.9%(53/l 13), stomach cancer 20.4%(23/113), breast cancer 11.5%(13/113), and unknown primary site 6.2%(7/113 cases), as a whole. In male, lung cancer was 55.9%(33/59), stomach cancer was 28.8%(17/59), and in female, lung cancer was 37% (20/54), breast cancer was 24.1% (13/54) of cases. 3) The cardinal symptoms were dyspnea(69%), cough(61%), chest pain(50%), weight loss(50%), anorexia(49%), sputum(43%), malaise(30%). 4) The pleural fluid findings were exudative in 94.4%(102/108), serosanguinous or bloody in 36~53%, unilateral involvement in 74.3%(84/l 13) of cases, and lymphocyte predominance (71 +/- 27%) in differential count of WBC. 5) CEA levels in pleural fluid or plasma were over 10ng/ml in 60.6% (40/66), and ADA levels in pleural fluid were under 40U/L in 95% (57/60) of cases. 6) The patients were managed by various methods, but the efficacy of treatment was uncertain. 7) The mean survival time was 12.7 +/- 13.5 weeks. CONCLUSION: It seems to be no effective treatment methods yet and the prognosis was very poor in this disease, so the objectives of diagnostic approaches and treatment methods should be directed to early diagnosis, treatment and prevention of curable disease. And we must make our best endeavors to lengthen the survival time and improve the quality of patients' life.