BACKGROUND: Lung cancer is an important public health problem because of rapidly increasing malignancy in both sexes in relation with high smoking rate in Korea. Despite advances in therapeutic modalities and supportive cares, 5-year survival rate has improved only marginally during the past 2 decades. Therefore, the early detection of lung cancer is strongly needed for batter prognosis and we conducted this study to review the clinical factors resulting in delayed diagnosis of lung cancer. METHOD: The clinical data such as presenting symptoms duration for diagnosis disease entities causing misdiagnosis or delayed diagnosis, were analyzed retrospectively in 154 patients with primary lung cancer diagnosed at Chungnam National university hospital from January to December in 1995. RESULTS: 63 patients(40.9%) out of 154 patients were delayed diagnosed with the duration of 6.3 months compared with 3.6 months in patients diagnosed without delay. In delayed diagnosed group, Cough