A retrospective study to examine the underlying causes of hemoptysis in patients undergoing diagnostic bronchoscopy was conducted. We found hemoptysis to be caused by bronchitis in 55 (37%) of 148, bronchogenic carcinoma in 28 (19%) of 148, tuberculosis in 10 (7%) of 148, and bronchiectasis in 1 (1%) of 148 patients. Compared with previous studies, it appears that hemoptysis is less likely to be caused by bronchiectasis or tuberculosis while hemoptysis caused by bronchitis has increased proportionately. The rate of occurrence of hemoptysis caused by bronchogenic carcinoma has not changed significantly. All patients with underlying bronchogenic carcinoma had a positive smoking history and abnormal chest roentgenogram. The rate of hemoptysis was not a good indicator of the underlying disease.